<PAGE>
 
                                                                   Exhibit 10.15
                                                                   -------------
                                 ANTHONY & CO.
                            OFFICE LEASE AGREEMENT
                                  COVER PAGE

TENANT:   ACCIPITER, INC.

DATED:    APRIL 9, 1997

For the purposes of this Lease Agreement by and between MILKSON ASSOCIATES, LLC
("Landlord"), by its agent, Anthony & Co., and ACCIPITER, INC. ("Tenant"), the
terms set forth below, when preceded by a capital letter, shall have the meaning
set forth in this Cover Page and in the Lease.


I.  TENANT AND LANDLORD INFORMATION

   A. Landlord:                     Milkson Associates, LLC
                                    a North Carolina Limited Liability Company

   B. Tenant:                       Accipiter, Inc.

   C. Tenant's Notice Address:      Suite 2000
                                    4000 Wake Forest Road
                                    Raleigh, NC 27609

   D. Tenant's Representative       Chris Evans

II. DESCRIPTION OF PREMISES

   A. Building:                     4000 Wake Forest Road

   B. Business Hours:               8:00 a.m. to 6:00 p.m.

   C. Premises:                     Suite 210, approximately 6,014 rentable
                                    square feet

   D. Permitted Use:                Office

III. TERM 

     A. Commencement Date:          May 1, 1997

     B. Expiration date:            April 30, 1999
<PAGE>
 
IV. RENT

     A. Advance Rent:               ____ N/A ____ ($___) representing the final
                                    monthly installment of Base Annual Rent for
                                    the ______ (___th) month of the lease term
                                    set forth in Article III.

     B. Base Annual Rent:           Eighty-seven Thousand, Two Hundred Three and
                                    no/100 Dollars ($87,203.00).

     C. Base Rental Rate:           Fourteen and 50/100 Dollars ($14.50) per
                                    square foot.

     D. Monthly Installment of      Seven Thousand, Two Hundred Sixty-six and
        Basic Rental Rent:          92/100 Dollars ($7,266.92).

     E. Security Deposit:           One Thousand, Twenty-one and 50/100 Dollars
                                    ($1,021.50).

V.   ADJUSTMENTS

     A. Adjustment Period           The Consumer Price Index as established for
        Consumer price Index:       the month of _____ N/A ____ of each year 
                                    following the Base Period Consumer Price
                                    Index as determined from the published
                                    figures.

     B. Base Period Consumer        The Consumer Price Index as established
        Price Index:                the month of ____ N/A ____.

     C. CPI Escalator:              ______ N/A ______ Percent (___%) subject to
                                    Three percent (3%) minimum and Five percent
                                    (5%) maximum.

     D. Base Operating and Real     _____ N/A _____ Dollars ($____) per
        Estate Tax Expenses:        square foot.

     E. Tenant's Pro Rata Share:    ____ N/A ____ Percent (___%) of the
                                    Building. Total rentable square footage is
                                    ____.

VI.  MISCELLANEOUS

     A. Broker:                     Jim Anthony

     B. Special Conditions          None

     C. Exclusive Rights            None



    TENANT:                            LANDLORD:

    ACCIPITER, INC.                    MILKSON ASSOCIATES, LLC
   
    by:__________________________      by:______________________

    Name:________________________

    Title:_______________________

    Date:________________________
         (Please Print or Type)

                                      -2-
<PAGE>
 
                                 ANTHONY & Co.
                                 OFFICE LEASE

     THIS LEASE ("Lease") is made April 9, 1997, between Milkson Associates, LLC
("Landlord") and ACCIPITER ("Tenant").  Landlord is a Limited Liability Company,
organized under the laws of North Carolina.

                                   ARTICLE 1
                                   PREMISES

1.01  Premises.  Landlord leases to Tenant Suite 200, 4000 Wake Forest Road,
Raleigh, North Carolina ("Premises") as outlined on the Floor Plan attached as
Exhibit A.  The Premises consists of approximately 6,014 square feet of rentable
---------                                                                     
space and 5,322 square feet of usable space in the building ("Building") in
which the Premises are located. The Building is shown as Exhibit B and is
                                                         ---------   
located on the land described in Exhibit C ("Land"). The Premises contain the
                                 --------- 
fixtures, improvements, and other property now installed plus any Landlord
Improvements required by Section 4.05 and Exhibit D.
                                          --------- 

1.02  Common Areas.  Tenant and its agents, employees, and invitees have the
nonexclusive right with others designated by Landlord to the free use of the
common areas ("Common Areas") in the Building and on the Land for the Common
Areas' intended and normal purpose.  Common Areas include elevators, sidewalks,
parking areas, driveways, hallways, stairways, public bathrooms, common
entrances, lobby, and other similar public areas and access ways.  Landlord may
change the Common Areas if the changes do not materially and unreasonably
interfere with Tenant's access to or use of the Premises.

                                  ARTICLE II
                                      USE

Tenant shall use the Premises for general office use, unless Landlord gives its
advance written consent to another use.  Landlord warrants that applicable laws,
ordinances, regulations, and restrictive covenants permit the Premises to be
used for general offices.  Tenant shall not create a nuisance or use the
Premises for any immoral or illegal purposes.

                                  ARTICLE III
                                      TERM

The Lease begins ("Commencement Date") on the earlier of: May 1, 1997, or

        (a) The date that Tenant takes possession and occupies the Premises; or


        (b) After (i) the Premises are substantially completed according to
            Section 4.01, (ii) Landlord gives the notice required by Section
            4.02, (iii) Landlord is ready, willing and able to deliver actual
            possession of the Premises, and (iv) the Target Date set in Section
            4.01 has arrived.

The Lease ends ("Expiration Date") at 11:59 pm on the last day of the calendar 
month June (2) years following the Commencement Date, unless terminated earlier 
under this Lease. Within thirty (30) days after the Commencement Date, the 
parties shall confirm in writing the Commencement and Expiration Dates.

4.01    Substantial Completion.  Landlord shall use its best efforts to 
substantially complete the Premises by May 1, 1997 ("Target Date"). 
Substantially complete means completing Landlord's Improvements (Section 4.05 
and Exhibit D) so that Tenant can use the Premises for their intended purposes.
    ---------

4.02    Notice.  Landlord shall give Tenant at least ten (10) days advance 
notice of the estimated substantial completion date if different from the Target
Date. If the estimated substantial completion date changes at any time after 
Landlord gives notice, then Landlord shall give ten (10) days advance notice of 
the new estimated substantial completion date.

4.03    Inspection and Punchlist.  Within 30 days after the Commencement Date, 
the parties shall inspect the Premises, have all systems demonstrated, and 
prepare a punchlist. The punchlist shall list incomplete, minor, or 
insubstantial details of construction; necessary mechanical adjustments; and 
needed finishing touches. Tenant's acceptance of possession of the Premises 
after such inspection shall be conclusive evidence that the Premises were in 
good order and satisfactory condition, except for any punchlist items. Landlord 
reserves the right to inspect and reasonably approve Tenant's improvements.

4.04    Delayed Possession.  Tenant may cancel this Lease if Landlord cannot 
deliver actual possession of the substantially complete Premises by one hundred 
and eighty (180) days after the Target Date. To cancel, Tenant must give notice 
to Landlord within sixty (60) days after the expiration of such one hundred and 
eighty day period and before Landlord gives notice to Tenant that the Premises 
are substantially complete. The one hundred and eighty (180) day period above 
shall be extended in the time equal to any period of delay caused by Tenant. 
Within thirty (30) days after cancellation, Landlord shall return to Tenant 
prepaid consideration including Rent and deposits, and neither party shall have 
any further rights or obligations under this Lease.



                                      -3-
<PAGE>
 
                                  ARTICLE IV
                            COMPLETION OF PREMISES

4.05  Landlord Improvements.  Landlord, at its expense, shall make improvements
to the Premises in accord with Exhibit D ("Landlord Improvements").  The
                               ---------                                
Landlord Improvements shall be completed in a good and workmanlike manner and
comply with all applicable laws, ordinances, rules, and regulations of
governmental authorities.

                                   ARTICLE V
                               RENT AND SECURITY

5.01  Base Rent. Tenant shall pay to Landlord Base Rent during the Term,
as follows:

    Months:                         Annual Base Rent:       Monthly Base Rent:

    One through Twelve,
      May 1, 1997 - April 30, 1998      $87,203.00               $7,266.92

    Thirteen through Twenty-four,
      May 1, 1998 - April 30, 1999      $89,819.09               $7,484.92

     The above schedule includes a three percent (3%) annual escalation.

     The Base Rent shall be paid:

     (a)  without advance notice, demand, offset, or deduction;

     (b)  by the first day of each month during the Term; and

     (c)  to Landlord at its address set forth in Section 13.03 or as Landlord
     may specify in writing to Tenant.

If the Term does not begin on the first day or end on the last day of a month,
the Base Rent for that partial month shall be prorated by multiplying the
monthly Base Rent by a fraction, the numerator of which is the number of days of
the partial month included in the Term and the denominator of which is the total
number of days in the full calendar month.

If Tenant fails to pay part or all of the Base Rent or Additional Rent within
ten (10) days after written notice that it is past due, the Tenant shall also
pay:

                                      -4-
<PAGE>
 
     (a)  a late charge equal to four percent (4%) of the unpaid Base Rent and
     Additional Rent, plus

     (b)  interest at eighteen percent (18%) per annum or the maximum then
     allowed by applicable law, whichever is less, on the remaining unpaid
     balance, retroactive to the date originally due until paid.

5.04  Personal Property Tax.  Before delinquency Tenant shall pay taxes assessed
during the Term against trade fixtures or personal property placed by Tenant in
the Premises.  If these taxes are assessed against the Building, Tenant shall
pay its share of the taxes to Landlord within ten (10) days after receiving
Landlord's written statement setting forth the amount of taxes applicable to
Tenant's property and the basis for the charge to Tenant.  Tenant's failure to
pay within the ten-day period shall entitle Landlord to the same remedies it has
upon Tenant's failure to pay Base Rent or Additional Rent.

5.05  Security Deposit.  The Tenant has deposited One Thousand, Twenty-one and
50/100 Dollars ($1,021.50) (Security Deposit) with Landlord to secure Tenant's
performance of its Lease obligations.  If Tenant defaults, Landlord may, after
giving five (5) days advance notice to Tenant, without prejudice to Landlord's
other remedies, apply part or all of the Security Deposit to cure Tenant's
default.  If Landlord so uses part or all of the Security Deposit, then Tenant
shall within ten (10) days after written demand, pay Landlord the amount used to
restore the Security Deposit to its original amount.  Landlord may mix the
Security Deposit with its own funds, and the Security Deposit shall not earn
interest thereon.  Any part of the Security Deposit not used by Landlord as
permitted by this paragraph shall be returned to Tenant within thirty (30) days
after the Lease ends.

                                  ARTICLE VI
                            AFFIRMATIVE OBLIGATIONS

6.01  Compliance with Laws.

     (a)  Landlord's Compliance.  Landlord warrants, that on the Commencement
     Date, the Premises will comply with all applicable laws, ordinances,
     rules, and regulations of governmental authorities ("Applicable
     Laws"). During the Term, Landlord shall comply with all Applicable
     Laws regarding the Premises and Building except to the extent Tenant
     must comply under Section 6.01(b).

     (b)  Tenant's Compliance.  Tenant shall comply with all Applicable Laws (i)
     regarding the physical condition of the Premises, but only to the
     extent the Applicable Laws pertain to the particular manner in which
     Tenant uses the Premises; or (ii) that do not relate to the physical
     condition of

                                      -5-
<PAGE>
 
     the Premises but relate to the lawful use of the Premises and with
     which only the occupant can comply, such as laws governing maximum
     occupancy, workplace smoking, and illegal business operations, such as
     gambling. Notwithstanding the foregoing, Tenant shall comply with any
     requirements imposed under the Americans with Disabilities Act of 1990
     ("ADA") which relate exclusively to the Premises.

6.02  Services and Utilities.

     (a)  Services.  Landlord shall provide at its expense, subject to
     reimbursement under Section 5.03:

          (i)    Heating, ventilation, and air conditioning ("HVAC") for the
          Premises during business hours to maintain temperatures for
          comfortable use and occupancy;

          (ii)   Automatic passenger elevators providing adequate service 
          leading to the floor on which the Premises are located;

          (iii)  Janitorial services to the Premises (all business days, Monday
          through Friday);

          (iv)   Hot and cold water sufficient for drinking, lavatory, toilet, 
          and ordinary cleaning purposes;

          (v)    Electricity to the Premises at all times that provides electric
          current in reasonable amounts necessary for normal office use,
          lighting, and HVAC;

          (vi)   Replacement of lighting tubes, lamp ballasts, and bulbs;

          (vii)  Extermination and pest control when necessary; and

          (viii) Maintenance of Common Areas in a manner consistent with other
          comparable office Buildings in the Raleigh, North Carolina
          area. The maintenance shall include cleaning, HVAC,
          illumination, snow shoveling, deicing, repairs, replacements,
          lawn care, and landscaping.

     (b)  Business Hours.  "Business Hours" means:

          (i)    Monday through Friday, 8:00 a.m. through 6:00 p.m., and

                                      -6-
<PAGE>
 
          (ii)   Saturday, 9:00 a.m. through 1:00 p.m., but excludes the 
          following holidays or the days on which the holidays are
          designated for observance: New Year's Day, Easter (Good
          Friday), Memorial Day, July Fourth, Labor Day, Thanksgiving
          Day, and Christmas Day.

     (c)  24 Hour Access.  Tenant, its employees, agents, and invitees shall 
     have access to the Premises, twenty-four (24) hours a day, seven (7)
     days a week. During non business hours Landlord may restrict access by
     requiring persons to show a badge or identification card issued by
     Landlord. Landlord shall not be liable for denying entry to any person
     unable to show the proper identification. Landlord may temporarily
     close the Building if required in an emergency. Landlord shall use its
     best efforts to close the Building during non business hours only. If,
     however, the Building must be closed during business hours, then the
     Base Rent and Additional Rent shall abate during any closing that
     lasts more than twenty-four (24) hours.

     (d)  Extra Services.  Landlord, shall have the right to monitor the 
     Tenant's use of electricity consumption within the Premises. Whenever
     Landlord knows that any tenant (including Tenant) is using extra
     services because of either non business-hours use or high electricity
     consumption installations, Landlord may directly charge that tenant
     for the extra use and exclude those charges from Operating Expenses.
     Extra services include:

          (i)    Non business-Hours Use.  Electricity required by Tenant 
          during non business hours shall be supplied upon reasonable
          advance verbal notice. If more than one tenant directly
          benefits from these services then the cost shall be allocated
          proportionately between or among the benefiting tenants based
          upon the amount of time each tenant benefits and the square
          footage each leases.

          (ii)   Excess Utility Use.  Tenant shall not place or operate in the
          Premises any electrically operated equipment or other
          machinery, other than typewriters, personal computers, adding
          machines, reproduction machines, and other machinery and
          equipment normally used in offices, unless Tenant receives
          Landlord's advance written consent. Landlord shall not
          unreasonably withhold or delay its consent, but Landlord may
          require payment for the extra use of electricity caused by
          operating this equipment or machinery. Landlord may require
          that special, high electricity consumption installations of
          Tenant such as computer or reproduction facilities (except
          personal computers or normal office photocopy machines) be
          separately sub-metered for electrical consumption at Tenant's
          cost.

                                      -7-
<PAGE>
 
          (iii)  Payment. Tenant's charges for the utilities provided under (i)
          and (ii) above shall be one hundred ten percent (110%) of Landlord's
          actual cost of labor and utilities and shall be Additional Rent.

          Tenant's failure to pay the charges in (i) and (ii) above within
          thirty (30) days of receiving a proper and correct invoice shall
          entitle Landlord to the same remedies it has upon Tenant's failure to
          pay Base Rent.

     (e)  Interruption of Services.  Landlord does not warrant that any services
     Landlord supplies will not be interrupted. Services may be interrupted
     because of accidents, repairs, alterations, improvements, or any
     reason beyond the reasonable control of Landlord, and such an interruption
     shall not:

          (i)    be considered an eviction or disturbance of Tenant's use and
          possession of the Premises;

          (ii)   make Landlord liable to Tenant for damages;

          (iii)  abate Base Rent or Additional Rent; or

          (iv)   relieve Tenant from performing Tenant's Lease obligations.

6.03  Repairs and Maintenance.

     (a)  Tenant's Care of Premises.  Tenant shall:

          (i)    keep the Premises and fixtures in good order;

          (ii)   make repairs or replacements to the Premises or Building needed
          because of Tenant's misuse or negligence, except to the extent that
          the repairs or replacements are covered by Landlord's insurance or the
          insurance Landlord is required to carry under this Lease, whichever is
          greater;

          (iii)  repair and replace special equipment or decorative treatments
          installed by or at Tenant's request and that serve the Premises
          only, except

                                      -8-
<PAGE>
 
                 (1)  to the extent the repairs or replacements are needed 
                 because of Landlord's misuse or primary negligence, and
                 are not covered by Tenant's insurance or the insurance
                 Tenant is required to carry under this Lease, whichever is
                 greater; or

                 (2)  if the Lease is terminated under Article IX (Loss of
                 Premises); and

          (iv)   not commit waste.

     (b)  Landlord's Repairs.  Except for repairs and replacements that Tenant
     must make under paragraph 6.03(a), Landlord shall pay for and make all
     other repairs and replacements to the Premises, Common Areas and Building
     (including Building fixtures and equipment).  Landlord shall make the
     repairs and replacements to maintain the Building in a condition consistent
     with other comparable office buildings in the Raleigh, North Carolina area.
     This maintenance shall include the roof, foundation, exterior walls,
     interior structural walls, all structural components, and all systems, such
     as mechanical, electrical, HVAC, and plumbing.

     (c)  Time for Repairs.  Repairs or replacements required under Sections
     6.03(a) or 6.03(b) shall be made within a reasonable time (depending
     on the nature of the repair or replacement needed) after receiving
     notice or having actual knowledge of the need for a repair or
     replacement.

     (d)  Surrendering the Premises.  Upon the Expiration Date or earlier
     termination of this Lease, Tenant shall surrender the Premises to
     Landlord in the same condition that the Premises were in on the
     Commencement Date except for:

          (i)    ordinary wear and tear;

          (ii)   damage by the elements, fire, and other casualty unless Tenant
          would be required to repair under paragraph 6.03(a);

          (iii)  condemnation;

          (iv)   damage arising from any cause not required to be repaired or
          replaced by Tenant; and

          (v)    alterations as permitted by this Lease unless consent was
          conditioned on their removal.

                                      -9-
<PAGE>
 
          On surrender Tenant shall remove from the Premises its personal
          property, trade fixtures, and any alterations required to be removed
          under Section 7.01 and repair any damage to the Premises caused by the
          removal.  Any items not removed by Tenant as required above shall be
          considered abandoned.  Landlord may dispose of abandoned items as
          Landlord chooses and bill Tenant for the cost of their disposal, minus
          any revenues received by Landlord for their disposal.

                                  ARTICLE VII
                             NEGATIVE OBLIGATIONS

7.01  Alterations.

     (a)  Definitions. "Alterations" means alterations, additions, 
     substitutions, installations, changes, and improvements, but excludes minor
     decorations and the Improvements Landlord is to make under Section 4.04 and
     Exhibit D.
     --------- 

     (b)  Consent.  Tenant shall not make Alterations without the Landlord's
     advance written consent. Landlord's consent shall not be unreasonably
     withheld or unduly delayed for nonstructural interior Alterations to
     the Premises that do not adversely affect the Building s appearance,
     value, and structural strength.

     (c)  Conditions of Consent.  Landlord may condition its consent in Section
     7.01(b) on all or any part of the following:

          (i)    Tenant shall furnish Landlord with reasonably detailed plans 
          and specifications of the alterations as requested by Tenant.

          (ii)   The Alterations shall be performed and completed

                 (1)  in accord with the submitted plans and specifications
                 approved by Tenant and Landlord,

                 (2)  in a workmanlike manner,

                 (3)  in compliance with all applicable laws, regulations, 
                 rules, ordinances, and other requirements of governmental
                 authorities,

                 (4)  using new materials and installations at least equally in
                 quality to the original Building materials and 
                 installations,

                                     -10-


<PAGE>
 
                 (5)  by not disturbing the quiet possession of the other 
                 tenants,

                 (6)  by not interfering with the construction, operation, or
                 maintenance of the Building, and

                 (7)  with due diligence;

          (iii)  tenant shall use workers and contractors who Landlord employs
          or approves in writing, which approval shall not be
          unreasonably withheld or unduly delayed;

          (iv)   Tenant shall modify plans and specifications because of
          reasonable conditions set by Landlord after reviewing the plans
          and specifications;

          (v)    Tenant's contractors shall carry builder's risk insurance in an
          amount then customarily carried by prudent contractors and
          workers' compensation insurance for its employees in statutory
          limits, naming Landlord as an additional insured, to the extent
          its interest may appear;

          (vi)   Tenant's workers or contractors shall work in harmony and not
          unreasonably interfere with Landlord's workers or contractors
          or other tenants and their workers or contractors;

          (vii)  Tenant shall, at Landlord's sole option, supply a lien and
          completion bond, bank letter of credit, or other security
          satisfactory to Landlord, in an amount equal to the estimated
          cost to insure Landlord against materials and mechanics' liens
          and against completion of the Alterations;

          (viii) Tenant shall give Landlord at least fifteen (15) days advance
          notice before beginning any alterations so that Landlord may
          post or record notices of nonresponsibility;

          (ix)   Upon demand Tenant shall give Landlord evidence that it 
          complied with any condition set by Landlord;

          (x)    If Tenant completes alterations, Tenant shall give Landlord
          complete as-built mylar drawings of the Alterations after they
          are finished; and

                                     -11-
<PAGE>
 
          (xi)   Tenant shall remove any unusual additions, alterations and 
          repair any damage from their removal by the Expiration Date.

     (d)  Payment and Ownership of the Alterations. Alterations made under this
     paragraph shall be at Tenant's expense. The Alterations shall belong to
     Landlord when this Lease ends except for those Alterations required by
     Landlord to be removed by Tenant, if any, under Section 7.01(c)(xi).
     Nevertheless, Tenant may remove its trade fixtures, furniture, equipment,
     and other personal property if Tenant promptly repairs any damage caused by
     their removal.

7.02  Assignment and Subleasing.

     (a)  Consent Required. Tenant shall not transfer, mortgage, encumber,
     assign, or sublease all or part of the Premises without Landlord's advance
     written consent. Landlord's consent to any assignment or sublease shall not
     be unreasonably withheld or unduly delayed.

     (b)  Reasonableness.  The Landlord's consent shall not be considered
     unreasonably withheld if:

          (i)    the proposed subtenant's or assignee's financial responsibility
          does not meet the same criteria Landlord uses to select comparable
          Building tenants;

          (ii)   the proposed subtenant's or assignee's business is not suitable
          for the Building considering the business of the other tenants and the
          Building's prestige; or

          (iii)  the proposed use is inconsistent with the use permitted by
          Article II.

     (c)  Procedure.

          (i)    Tenant must provide Landlord in writing:

                 (1)  the name and address of the proposed subtenant or 
                 assignee;

                 (2)  the nature of the proposed subtenant's or assignee's 
                 business it will operate in the Premises;

                 (3)  the terms of the proposed sublease or assignment; and

                                      -12-
<PAGE>
 
                 (4)  reasonable financial information so that Landlord can
                 evaluate the proposed subtenant or assignee.

          (ii)   Landlord shall, within ten (10) business days after receiving
          the information under Section 7.02(c)(i), give notice to Tenant to
          permit or deny the proposed sublease or assignment. If Landlord denies
          consent, it must explain the reasons for the denial. If Landlord does
          not give notice within the ten (10) business-day period, then Tenant
          may sublease or assign part or all of the Premises upon the terms
          described in the information submitted by Tenant under Section
          7.02(c)(i).

     (d)  Affiliates.  Notwithstanding Section 7.02(a), (b), and (c), Tenant may
     assign or sublease part or all of the Premises without Landlord's consent
     to:

          (i)    any corporation or partnership that controls, is controlled 
          by, or is under common control with, Tenant; or

          (ii)   any corporation resulting from the merger or consolidation with
          Tenant or to any entity that acquires all of Tenant's assets or stock
          as a going concern of the business that is being conducted on the
          Premises, as long as the assignee or subleases is a bona fide entity
          and assumes the obligations of Tenant.

     (e)  Conditions.  Any subleases and assignments by Tenant are also subject
     to the following:

          (i)    The terms of this Lease;

          (ii)   The term of any sublease shall not extend beyond the Term;

          (iii)  Tenant shall remain liable for all Lease obligations;

          (iv)   Consent to one sublease or assignment does not waive the 
          consent requirements for future assignments or subleases; and

          (v)    Any consideration ("Excess Consideration") received by Tenant
          from an assignment or sublease that exceeds the amount Tenant must pay
          Landlord, which amount is to be prorated where a part of the Premises
          is subleased or assigned, shall also be paid to Landlord. Tenant shall
          pay this Excess Consideration to Landlord at the end of each calendar
          month during which Tenant collects any Excess Consideration. Each
          payment shall be sent

                                      -13-
<PAGE>
 
          with a detailed statement showing the total consideration paid by the
          subtenant or assignee. Landlord shall have the right to audit Tenant's
          books and records to verify the accuracy of the detailed statement.

                                 ARTICLE VIII
                                   INSURANCE

8.01  Insurance.

     (a)  Landlord's Building Insurance. Landlord shall keep the Building,
     including the Landlord Improvements insured against damage and
     destruction by fire, earthquake, vandalism, and other perils in the
     amount of the full replacement value of the Building, as the value
     may exist from time to time.

     (b)  Property Insurance. Each party shall keep its personal property and
     trade fixtures in the Premises and Building insured with "all risks"
     insurance in an amount to cover one hundred percent (100%) of the
     replacement cost of the property and fixtures. Tenant shall also keep
     any non-Building standard improvements made to the Premises at
     Tenant's request insured to the same degree as Tenant's personal
     property. Tenant's property insurance shall also provide for business
     interruption/extra expense coverage in sufficient amounts.

     (c)  Liability Insurance. Each party shall maintain contractual and
     comprehensive general liability insurance, including limits of no
     less than $1,000,000 per occurrence/$2,000,000 aggregate per location
     subject to no deductible contractual liability covering the
     indemnities specified herein. This policy must be written on an
     occurrence basis.

     Policy shall be endorsed to name Landlord as additional insured.
     Definition of additional insured shall include all Partners,
     Officers, Directors, Employees, agents and representatives of the
     named entity including its managing agent. Further, coverage for the
     additional insured shall apply on a primary basis irrespective of any
     other insurance, whether collectible or not.

     (d)  Workers Compensation and Employee Liability Insurance. Affording
     coverage under the Workers Compensation laws of the State of North
     Carolina and Employers Liability coverage subject to a limit of no
     less than $100,000 each employee, $100,000 each accident, $500,000
     policy limit.

                                      -14-
<PAGE>
 
     (e)  Umbrella Liability insurance. Tenant shall maintain umbrella
     liability insurance at not less than a $3,000,000 limit providing
     excess coverage over all limits and coverage noted in Sections 8.01.c
     and 8.01.d above. This policy shall be written on an occurrence
     basis.

     (f)  Waiver of Subrogation. Anything in this Lease to the contrary
     notwithstanding, Landlord and Tenant hereby waive and release each
     other of and from any and all right of recovery, claim, action or
     cause of action, against each other, their agents, officers and
     employees, for any loss or damage that may occur to the Premises,
     improvements to the Building, or personal property within the
     Building, by reason of fire or the elements, regardless of cause or
     origin, including negligence of Landlord or Tenant and their agents,
     officers and employees. Landlord and Tenant agree immediately to give
     their respective insurance companies which have issued policies of
     insurance covering all risk of direct physical loss, written notice
     of the terms of the mutual waivers contained in this Section, and to
     have the insurance policies properly endorsed, if necessary, to
     prevent the invalidation of the insurance coverage by reason of the
     mutual waivers. The waiver does not apply to claims caused by a
     party's willful misconduct.

     If despite a party's best efforts it cannot find an insurance company
     meeting the criteria in Section 8.01(f) that will give the waiver at
     reasonable commercial rates, then it shall give notice to the other
     party within thirty (30) days after the Commencement Date. The other
     party shall then have thirty (30) days to find an insurance company
     that will issue the waiver. If the other party also cannot find such
     an insurance company, then both parties shall be released from their
     obligations to obtain the waiver.

     (g)  Increase in Insurance. If due to Tenant's particular use of the
     Premises, Landlord's insurance rates are increased, Tenant shall pay
     the increase. In addition, the amounts of coverage required by this
     Lease are subject to review by Landlord at the end of each Adjustment
     Period. At each review, if necessary to maintain the same level of
     coverage that existed on the Commencement Date, the amounts of
     coverage shall be increased to the lesser of:

          (i)    the amounts of coverage carried by prudent landlords and 
          tenants of comparable office buildings in the Raleigh, North Carolina
          area; or

          (ii)   twenty-five percent (25%) higher than the previous insurance
          amounts.

                                      -15-
<PAGE>
 
     (h)  Insurance Criteria. Insurance policies required by this Lease shall:

          (i)    be issued by insurance companies licensed to do business in the
          state of North Carolina with general policyholder's ratings of at
          least A and a financial rating of at least XI in the most current
          Best's Insurance Reports available on the date of this Lease;

          (ii)   name the non procuring party as an additional insured as its
          interest may appear (other landlords or tenants may also be added as
          additional insurers in a blanket policy);

          (iii)  provide that the insurance not be canceled or materially 
          changed in the scope or amount of coverage unless thirty (30) days'
          advance notice is given to the non procuring party;

          (iv)   be primary policies - not as contributing with, or in excess
          of, the coverage that the other party may carry;
      
          (v)    be permitted to be carried through a "blanket policy" or
          "umbrella" coverage;

          (vi)   have property deductibles not greater than $5,000; and
      
          (vii)  be maintained during the entire Term.

     (i)  Evidence of Insurance. By the Commencement Date and upon each renewal
     of its insurance policies, Tenant shall give copies of certificates of
     insurance to Landlord. The certificate shall specify amounts, types of
     coverage, the waiver of subrogation, and the insurance criteria listed in
     Section 8.01(f). The policies shall be renewed or replaced and maintained
     by Tenant. If Tenant fails to give the required certificate within thirty
     (30) days after the notice of demand for it, Landlord may obtain and pay
     for that insurance, but is not obligated to do so, and receive
     reimbursement from the party required to have the insurance.

8.02  Indemnification.

     (a)  Tenant's Indemnity. Tenant indemnifies, defends, and holds Landlord
     harmless from claims, including but not limited to claims:
  
          (i)    for personal injury, death, or property damage;
  
          (ii)   for incidents occurring in or about the Premises or Building;
          and

                                      -16-
<PAGE>
 
          (iii)  caused by the negligence or willful misconduct of Tenant,
          its agents, employees, or invitees.

          When the claim is caused by the joint negligence or willful misconduct
          of Tenant and Landlord or Tenant and a third party unrelated to
          Tenant, except Tenant's agents, employees, or invitees, Tenant's duty
          to defend, indemnify, and hold Landlord harmless shall be in
          proportion to Tenant's allocable share of the joint negligence or
          willful misconduct.

     (b)  Landlord's Indemnity. Landlord indemnifies, defends, and holds Tenant
     harmless from claims:

          (i)   for personal injury, death, or property damage;
         
          (ii)   for incidents occurring in or about the Premises or Building;
          and
          
          (iii)  caused by the negligence or willful misconduct of Landlord, its
          agents, employees, or invitees.
         
     When the claim is caused by the joint negligence or willful misconduct of
     Landlord and Tenant or Landlord and a third party unrelated to Landlord,
     except Landlord's agents, employees, or invitees, Landlord's duty to
     defend, indemnify, and hold Tenant harmless shall be in proportion to
     Landlord's allocable share of the joint negligence or willful misconduct.

     (c) Release of Claims. Notwithstanding Section 8.02(a) and (b), the parties
     release each other from any claims either party ("Injured Party") has
     against the other to the extent the claim is covered by the Injured Party's
     insurance.

8.03  Limitation of Landlord's Liability.

     (a)  Transfer of Premises.  If the Building is sold or transferred,
     voluntarily or involuntarily, Landlord's Lease obligations and liabilities
     accruing after the transfer shall be the sole responsibility of the new
     owner, and

          (i)    the new owner expressly agrees in writing to assume Landlord's
          obligations; and
    
          (ii)   the Tenant's funds in the hands of Landlord, such as the
          Security Deposit, shall be given to the new owner.

                                      -17-
<PAGE>
 
     (b)  Liability for Money Judgment. If Landlord, its employees, officers,
     directors or partners are ordered to pay Tenant a money judgment
     because of Landlord's default, Tenant's sole remedy to satisfy the
     judgment shall be to execute against Landlord's interest in the
     Building and Land. Under no circumstance will Landlord, or its
     officers, directors, partners or employees be personally liable for
     any money judgment.

                                  ARTICLE IX
                               LOSS OF PREMISES

9.01  Damages.

     (a)  Definition.  "Relevant Space" means:

          (i)    the Premises, excluding Tenant's fixtures installed by or at
          the request of Tenant;
    
          (ii)   access to the Premises; and
    
          (iii)  any part of the Building that provides essential services to
          the Premises.

     (b)  Repair of Damage.  If the Relevant Space is damaged in part or whole
     from any cause and the Relevant Space can be substantially repaired and
     restored within one hundred eighty (180) days from the date of the damage
     using standard working methods and procedures, Landlord shall at its
     expense promptly and diligently repair and restore the Relevant Space to
     substantially the same condition as existed before the damage. This repair
     and restoration shall be made within one hundred eighty (180) days from the
     date of the damage unless the delay is due to causes beyond Landlord's
     reasonable control.
     
     If the Relevant Space cannot be repaired and restored within the one
     hundred eighty (180) day period, then either party, may, within thirty (30)
     days after determining that the repairs and restoration cannot be made
     within one hundred eighty (180) days, cancel the Lease by giving notice to
     the other party. Nevertheless, if the Relevant Space is not repaired and
     restored within one hundred eighty (180) days from the date of the damage,
     then Tenant may cancel the Lease at any time within thirty (30) days after
     the one hundred eightieth (180th) day. Tenant shall not be able to cancel
     this Lease if its willful misconduct causes the damage unless Landlord is
     not promptly and diligently repairing and restoring the Relevant Space.

                                      -18-
<PAGE>
 
     (c)  Determining the Extent of Damage.  If the parties cannot agree in
     writing whether the repairs and restoration will take more than one
     hundred eighty (180) days to make, then the determination will be
     made by Landlord's architect.
    
     (d)  Abatement.  Unless the damage is caused by Tenant's willful
     misconduct, the Base Rent and Additional Rent shall abate in
     proportion to that part of the Premises that is unfit for use in
     Tenant's business. The abatement shall consider the nature and extent
     of interference to Tenant's ability to conduct business in the
     Premises and the need for access and essential services. The
     abatement shall continue from the date the damage occurred until ten
     (10) business days after Landlord completes the repairs and
     restoration to the Relevant Space or the part rendered unusable and
     notice to Tenant that the repairs and restoration are completed, or
     until Tenant again uses the Premises or the part rendered unusable,
     whichever is first.

     (e)  Tenant's Property.  Notwithstanding anything else in this Article IX,
     Landlord is not obligated to repair or restore damage to Tenant's
     trade fixtures, furniture, equipment, or other personal property, or
     any Tenant improvements.
   
     (f)  Damage to Building.  If:
   
          (i)    more than twenty percent (20%) of the Building is damaged and
          the Landlord decides not to repair and restore the Building;
   
          (ii)   any mortgagee of the Building shall not allow adequate
          insurance proceeds for repair and restoration;
   
          (iii)  the damage is not covered by Landlord's insurance; or
   
          (iv)   the Lease is in the last twelve (12) months of its Term, then
          Landlord may cancel this Lease. To cancel, Landlord must give
          notice to Tenant within thirty (30) days after the Landlord
          knows of the damage. The notice must specify the cancellation
          date, which shall be at least thirty (30) but not more than
          sixty (60) days after the date notice is given.

     (g)  Cancellation.  If either party cancels this Lease as permitted above,
     then this Lease shall end on the day specified in the cancellation
     notice. The Base Rent, Additional Rent, and other charges shall be
     payable up to the cancellation date and shall account for any
     abatement. Landlord shall promptly refund to Tenant any prepaid,
     unaccrued Base Rent and 

                                      -19-
<PAGE>
 
     Additional Rent, accounting for any abatement, plus Security Deposit,
     if any, less any sum then owing by Tenant to Landlord.

9.02  Condemnation.

     (a)  Definitions.  The terms "eminent domain," "condemnation," "taken," and
     the like in Section 9.02 include takings for public or quasi-public
     use and private purchases in place of condemnation by any authority
     authorized to exercise the power of eminent domain.
   
     (b)  Entire Taking.  If the entire Premises or the portions of the Building
     required for reasonable access to, or the reasonable use of, the
     Premises are taken by eminent domain, this Lease shall automatically
     end on the earlier of:
   
          (i)    the date title vests; or
   
          (ii)   the date Tenant is dispossessed by the condemning authority.
   
     (c)  Partial Taking.  If the taking of a part of the Premises materially
     interferes with Tenant's ability to continue its business operations
     in substantially the same manner and space then Tenant may terminate
     this Lease on the earlier of:
   
          (i)    the date when title vests;
   
          (ii)   the date Tenant is dispossessed by the condemning authority; or
   
          (iii)  sixty (60) days following notice to Tenant of the date when
          vesting or dispossession is to occur.
   
     If there is a partial taking and this Lease continues, then the Lease
     shall end as to the part taken and the Base Rent and Additional Rent
     shall abate in proportion to the part of the Premises taken and
     Tenant's pro rata share shall be equitably reduced.
   
     (d)  Termination by Landlord.  If title to a part of the Building other
     than the Premises is condemned, and in the Landlord's reasonable
     opinion, the Building should be restored in a manner that materially
     alters the Premises, Landlord may cancel this Lease by giving notice
     to Tenant. Cancellation notice shall be given within sixty (60) days
     following the date title vested. This Lease shall end on the date
     specified in the cancellation notice, which date shall be at least
     thirty (30) days but not more than ninety (90) days alter the notice
     is given.

                                      -20-
<PAGE>
 
     (e)  Rent Adjustment.  If the Lease is canceled as provided in Sections
     9.02(b), (c), or (d), then the Base Rent, Additional Rent, and other
     charges shall be payable up to the cancellation date, and shall
     account for any abatement. Landlord, considering any abatement, shall
     promptly refund to Tenant any prepaid, unaccrued Base Rent and
     Additional Rent plus Security Deposit, if any, less any sum then
     owing. by Tenant to Landlord.
   
     (f)  Repair.  If the Lease is not canceled as provided for in Sections
     9.02(b), (c), or (d), then Landlord at its expense shall promptly
     repair and restore the Premises to the condition that existed
     immediately before the taking, except for the part taken, to render
     the Premises a complete architectural unit, but only to the extent of
     the:
   
          (i)    condemnation award received for the damage; and
   
          (ii)   the Landlord's original obligation under Section 4.05 and 
          Exhibit  D.
          ----------
   
     (g)  Awards and Damages.  Landlord reserves all rights to damages paid
     because of any partial or entire taking of the Premises. Tenant
     assigns to Landlord any right Tenant may have to the damages or
     award. Further, Tenant shall not make claims against Landlord or the
     condemning authority for damages. Notwithstanding anything else in
     this Paragraph 9.02(g), Tenant may claim and recover from the
     condemning authority a separate award for Tenant's moving expenses,
     business dislocation damages, Tenant's personal property and
     fixtures, the unamortized costs of leasehold improvements paid for by
     Tenant, excluding the Landlord's Improvements, and any other award
     that would not substantially reduce the award payable to Landlord.
     Each party shall seek its own award, as limited by this provision, at
     its own expense, and neither shall have any right to the award made
     to the other.
   
     (h)  Temporary Condemnation.  If part or all of the Premises are condemned
     for a limited period of time ("Temporary Condemnation"), this Lease
     shall remain in effect. The Base Rent and Additional Rent and
     Tenant's obligations for the part of the Premises taken shall abate
     during the Temporary Condemnation in proportion to the part of the
     Premises that Tenant is unable to use in its business operations as a
     result of the Temporary Condemnation. Landlord shall receive the
     entire award for any Temporary Condemnation.

                                      -21-
<PAGE>
 
                                   ARTICLE X
                                    DEFAULT

10.01  Tenant's Default.

     (a)  Defaults. Each of the following constitutes a default ("Default"):
    
          (i)    Tenant's failure to pay Base Rent or Additional Rent within
          five (5) days after it is past due and payable;
    
          (ii)   Tenant's failure to pay Base Rent or Additional Rent by the due
          date, at any time during a calendar year in which Tenant has
          already received two (2) notices of its failure to pay Base
          Rent or Additional Rent by the due date;
    
          (iii)  Tenant's failure to perform or observe any other Tenant
          obligation after a period of thirty (30) business days or the
          additional time, if any, that is reasonably necessary to
          promptly and diligently cure the failure, after it receives
          notice from Landlord setting forth in reasonable detail the
          nature and extent of the failure and identifying the applicable
          Lease provision(s);
      
          (iv)   Tenant's abandoning or vacating the Premises;
      
          (v)    Tenant's failure to vacate or stay any of the following within
          sixty (60) days after they occur:
      
                 (1)  a petition in bankruptcy is filed by or against Tenant;
      
                 (2)  Tenant is adjudicated as bankrupt or insolvent;
      
                 (3)  a receiver, trustee, or liquidator is appointed for all
                 or a substantial part of Tenant's property; or
      
                 (4)  Tenant makes an assignment for the benefit of creditors.

10.02 Landlord's Remedies.

     (a)  Remedies.  Landlord in addition to the remedies given in this Lease or
     under the law, may do any one or more of the following if Tenant
     commits a Default under Section 10.01:
   
          (i)    end this Lease, and Tenant shall then surrender the Premises to
          Landlord;

                                      -22-
<PAGE>
 
          (ii)   enter and take possession of the Premises either with or
          without process of law and remove Tenant, with or without
          having ended the Lease;

          (iii)  alter locks and other security devices at the Premises; and

     Tenant waives claims for damages by reason of Landlord's reentry,
repossession, or alteration of locks or other security devices and for damages
by reason of any legal process.

     (b)  No Surrender.  Landlord's exercise of any of its remedies or its
     receipt of Tenant's keys shall not be considered an acceptance or
     surrender of the Premises by Tenant. A surrender must be agreed to in
     writing signed by both parties.
    
     (c)  Rent.  If Landlord terminates this Lease or Tenant's right to possess
     the Premises because of a Default, Landlord may hold Tenant liable
     for Base Rent, Additional Rent, and other indebtedness accrued to the
     date the Lease expires or is terminated. Tenant shall also be liable
     for the Base Rent, Additional Rent and other indebtedness that
     otherwise would have been payable by Tenant during the remainder of
     the Term had there been no default, reduced by any sums Landlord
     receives by reletting the Premises during the Term.
    
     (d)  Other Expenses.  Tenant shall also be liable for that part of the
     following sums paid by Landlord and attributable to that part of the
     Term ended due to Tenant's Default:

          (i)    reasonable broker's fees incurred by Landlord for reletting
          part or all of the Premises prorated for that part of the
          reletting Term ending concurrently with the then current Term
          of this Lease;

          (ii)   the cost of removing and storing Tenant's property;

          (iii)  the cost of repairs, alterations, and remodeling necessary to
          put the Premises in a condition reasonably acceptable to a new Tenant;
          and

          (iv)   other necessary and reasonable expenses incurred by Landlord in
          enforcing its remedies, including, without limitation, reasonable
          attorneys fees.

                                      -23-
<PAGE>
 
     (e)  Payment.  Tenant shall pay the sums due in Sections 10.02(c) and (d)
     within thirty (30) days of receiving Landlord's proper and correct invoice
     for the amounts.

     (f)  Reletting.  Landlord may relet for a shorter or longer period of time
     than the Lease Term and make any necessary repairs or alterations. Landlord
     may relet on any reasonable terms including a reasonable amount of free
     rent.

10.03  Self-Help.  If Tenant defaults, Landlord may, without being obligated and
without waiving the Default, cure the Default, and may enter the Premises to do
so. Tenant shall pay Landlord, upon demand, as Additional Rent, all costs,
expenses and disbursements incurred by Landlord.

10.04  Survival.  The remedies permitted by this Article X and the parties'
indemnities in Section 8.02 shall survive the Expiration Date or earlier
termination of this Lease.

                                  ARTICLE XI
                                NON DISTURBANCE

11.01  Subordination.

     (a)  Mortgages.  Subject to Section 11.01(b), this Lease is subordinate to
     prior or subsequent mortgages covering the Building.

     (b)  Foreclosures.  If any mortgage is foreclosed, then:

          (i)    This Lease shall continue;

          (ii)   Tenant's quiet possession shall not be disturbed if Tenant is
          not in Default;

          (iii)  Tenant will attorn to and recognize the mortgagee or purchaser
          at foreclosure sale (Successor Landlord) as Tenant's landlord for the
          remaining Term; and

          (iv)   The Successor Landlord shall not be bound by:

                 (1) any payment of Base Rent or Additional Rent for more than
                 one month in advance, except the Security Deposit and free
                 rent, if any, specified in the Lease,

                                      -24-
<PAGE>
 
                 (2) any amendment, modification, or ending of this Lease
                 without Successor Landlord's consent after the Successor
                 Landlord's name is given to Tenant unless the amendment,
                 modification, or ending is specifically authorized by the
                 original Lease and does not require Landlord's prior agreement
                 or consent, and

                 (3) any liability for any act or omission of a prior Landlord.

     (c) Self-Operating. This Section 11.01 is self-operating. However, Tenant
     shall promptly execute and deliver any documents needed to confirm this
     arrangement.

11.02  Estoppel Certificate.

     (a)  Obligation.  Tenant shall from time to time, within ten (10) business
     days after receiving a written request from Landlord, execute and deliver
     to Landlord a written statement which may be relied upon by Landlord and
     any third party with whom the Landlord is dealing and which shall certify:

          (i)    the accuracy of the Lease document;

          (ii)   the Commencement and Expiration Dates of the Lease;

          (iii)  that the Lease is unmodified and in full effect or in full
          effect as modified, stating the date and nature of the modification;

          (iv)   whether to the Tenant's knowledge the Landlord is in default or
          whether the Tenant has any claims or demands against Landlord, and, if
          so, specifying the Default, claim, or demand; and

          (v)    to other correct and reasonably ascertainable facts that are
          covered by the Lease terms.

     (b) Remedy. The Tenant's failure to comply with its obligations in Section
     11.02(a) shall be a Default, except that the cure period for this Default
     shall be five (5) business days after the Tenant receives notice of the
     Default.

11.03  Quiet Possession.  If Tenant is not in default, and subject to the Lease
terms, Landlord warrants that Tenant's peaceable and quiet enjoyment of the
Premises shall not be disturbed by anyone claiming by or through Landlord.

                                      -25-
<PAGE>
 
                                  ARTICLE XII
                               LANDLORD'S RIGHTS

12.01  Rules.

     (a)  Rules.  Tenant, its employees and invitees, shall comply with:

          (i)    the Rules attached as Exhibit E; and
                                       ---------     

          (ii)   reasonable modifications and additions to the Rules adopted by
          Landlord.

     (b)  Conflict with Lease. If a Rule issued under Section 12.01(a) conflicts
     with or is inconsistent with any Lease provision, the Lease provision
     controls.

     (c)  Enforcement. Although Landlord is not responsible for another tenant's
     failure to observe the Rules, Landlord shall not unreasonably enforce the
     Rules against Tenant.

12.02  Mechanic's Liens.

     (a)  Discharge Lien.  Tenant shall, within twenty (20) days after receiving
     notice of any mechanic's lien for material or work claimed to have been
     furnished to the Premises on Tenant's behalf and at Tenant's request:

          (i)    discharge the lien; or

          (ii)   post a bond equal to the amount of the disputed claim with
          companies reasonably satisfactory to Landlord.

     If Tenant posts a bond, it shall contest the validity of the lien.
     Tenant shall indemnify, defend, and hold Landlord harmless from losses
     incurred from these liens.

     (b)  Landlord's Discharge.  If Tenant does not discharge the lien or post
     the bond within the twenty (20) day period, Landlord may pay any amounts,
     including interest and legal fees, to discharge the lien.  Tenant shall
     then be liable to Landlord for the amounts paid by Landlord as Additional
     Rent.

     (c)  Consent not Implied.  This Section 12.02 is not a consent to subject
     Landlord's property to these liens.

                                      -26-
<PAGE>
 
12.03  Right to Enter.

     (a)  Permitted Entries.  Landlord and its agents, servants, and employees
     may enter the Premises at reasonable times, and at any time if an
     emergency, without charge, liability, or abatement of Base Rent, to:

          (i)    examine the Premises;

          (ii)   make repairs, alterations, improvements, and additions either
          required by the Lease or advisable to preserve the integrity, safety,
          and good order of part or all of the Premises or Building;

          (iii)  provide janitorial and other services required by the Lease;

          (iv)   comply with Applicable Laws;

          (v)    show the Premises to prospective lenders or purchasers;

          (vi)   post notices of non responsibility;

          (vii)  remove any Alterations made by Tenant in violation of Section
     7.01; and

          (vi)   post "For Sale" signs and, during the one-hundred twenty (120)
          days immediately before this Lease ends, post "For Lease" signs.

     (b)  Entry Conditions.  Notwithstanding Section 12.03(a), entry is
     conditioned upon Landlord:

          (i)    giving Tenant at least twenty-four (24) hours advance notice,
          except in an emergency;

          (ii)   promptly finishing any work for which it entered; and

          (iii)  causing the least practical interference to Tenant's business.

12.04  Holdover.

     (a)  Holdover Status.  If Tenant continues occupying the Premises after the
     Term ends ("Holdover") then:

          (i)    if the Holdover is with Landlord's written consent, it shall
          be a month-to-month tenancy, terminable on thirty (30) days advance
          notice by either party. Tenant shall pay at the beginning of each

                                      -27-
<PAGE>
 
          month Base Rent and Additional Rent that is five percent (5%) higher
          than the amount due in the last full month immediately preceding the
          Holdover period unless Landlord specifies a lower or higher Rent and
          Additional Rent in the written consent;

          (ii)   if the Holdover is without Landlord's written consent, then
          Tenant shall be a tenant-at-sufferance. Tenant shall pay by the first
          day of each month twice the amount of Base Rent and Additional Rent
          due in the last full month immediately preceding the Holdover period
          and shall be liable for any damages suffered by Landlord because of
          Tenant's Holdover, Landlord shall retain its remedies against Tenant
          who holds over without written consent.

     (b)  Holdover Terms.  The Holdover shall be on the same terms and 
     conditions of the Lease except:

          (i)    the Term;

          (ii)   Base Rent and Additional Rent;

          (iii)  the extension Term is deleted;

          (iv)   the Quiet Possession provision is deleted;

          (v)    Landlord's obligation for services and repairs is deleted; and

          (vi)   consent to an assignment or sublease may be unreasonably 
          withheld and delayed.

12.05  Signs.  Tenant shall not place or have placed any other signs, listings,
advertisements, or any other notices anywhere in the Building without Landlord's
prior written consent.

12.06  Right to Relocate.  If the demised Premises comprise less than fifty
percent (50%) of the floor where located, Landlord, at its option, may
substitute for the Demised Premises other space  (hereafter called "Substitute
Premises") within the project before the commencement date or at any time during
the term or any extension of their lease.  Insofar as reasonably possible, the
Substitute Premises shall have a comparable square foot area and a configuration
substantially similar to the Demised Premises.

Landlord shall give Tenant at least sixty (60) days written notice of its
intention to relocate Tenant to the Substitute Premises.  This notice will be
accompanied by a 

                                      -28-
<PAGE>
 
floor plan of the Substitute Premises. After such notice, Tenant Shall have ten
(10) days within which to agree with Landlord on the proposed new space and
unless such agreement is reached within such period of time, this lease shall
terminate at the end of the sixty (60) day period of time following the
aforesaid notice. In the event suitable substitute space is not available after
Landlord's written notice then either party may terminate this lease with sixty
(60) days advance written notice.

Landlord agrees to construct or alter, at its own expense, the Substitute
Premises as expeditiously as possible so that they are in substantially the same
condition that the Demised Premises were in immediately prior to the relocation.
Landlord shall have the right to reuse the fixtures, improvements, and
alterations used in the Demised Premises.  Tenant agrees to occupy the
Substitute Premises as soon as Landlord's work is substantially completed.

Landlord shall pay Tenant's reasonable cost of moving Tenant's furnishings,
trade fixtures, and inventory to the Substitute Premises.  Except as provided
herein, Tenant agrees that all of the obligations of this lease, including the
payment of rent, will continue despite Tenant's location.  Tenant's rent shall
abate from the date the Demised Premises are closed until the date the
Substitute Premises are open for business.  Tenant agrees to use all reasonable
efforts to open for business in the Substitute Premises as quickly as is
reasonably possible under the circumstance.

Except as provided above, Landlord shall not be liable or responsible in any way
for damages or injuries suffered by Tenant pursuant to the relocation in
accordance with this provision including, but not limited to, loss of goodwill,
business, or profits.

                                 ARTICLE XIII
                                 MISCELLANEOUS

13.01  Broker's Warranty.  The parties warrant that Anthony and Co. is the only
broker they dealt with on this Lease.  The party who breaches this warranty
shall defend, hold harmless, and indemnity the non breaching party from any
claims or liability arising from the breach.  Landlord is solely responsible for
paying the commission of Anthony & Co.

13.02  Attorney's Fees.  In any litigation between the parties regarding this
Lease, the losing party shall pay to the prevailing party all reasonable
expenses and court costs including attorneys' fees incurred by the prevailing
party.  A party shall be considered the prevailing party if:

     (a)  it initiated the litigation and substantially obtains the relief it
     sought, either through a judgment or voluntary action before (after it is
     scheduled) trial or judgment;

                                      -29-
<PAGE>
 
     (b)  the other party withdraws its action without substantially obtaining
     the relief it sought; or

     (c)  it did not initiate the litigation and judgment it entered for either
     party, but without substantially granting the relief sought.

13.03 Notices. Unless a Lease provision expressly authorizes verbal notice, all
notices under this Lease shall be in writing and sent by registered or certified
mail, postage prepaid, as follows:


     To Tenant:     ACCIPITER       (mailing address)
                    4000 Wake Forest Road
                    Suite 210
                    Raleigh, NC 27609


                         and

     To Landlord:
                    Milkson Associates, LLC
                    c/o Anthony & Co.
                    Post Office Box 10810
                    Raleigh, NC 27605-0810
                    Attn: Property Management
                    (919) 832-1110


Either party may change these persons or addresses by giving notice as provided
above.  Tenant shall also give required notices to Landlord's mortgagee after
receiving notice from Landlord of the mortgagee's name and address.  Notice
shall be considered given and received on the latest original delivery or
attempted delivery date as indicated on the postage receipt(s) of all persons
and addresses to which notice is to be given.

13.04  Partial Invalidity.  If any Lease provision is invalid or unenforceable
to any extent, then that provision and the remainder of this Lease shall
continue in effect and be enforceable to the fullest extent permitted by law.

                                      -30-
<PAGE>
 
13.05  Waiver.  The failure of either party to exercise any of its rights Is 
not a waiver of those rights. A party waives only those rights specified in
writing and signed by the party waiving its rights.

13.06  Binding on Successors.  This Lease shall bind the parties' heirs,
successors, representatives, and permitted assigns.

13.07  Governing Law.  This Lease shall be governed by the laws of the state in
which the Building is located.

13.08  Lease Not an Offer.  Landlord gave this Lease to Tenant for review. It is
not an offer to lease. This Lease shall not be binding unless signed by both
parties and an originally signed counterpart is delivered to Tenant by June 10,
1996.

13.09  Recording.  Recording of this Lease is prohibited except as allowed in 
this paragraph. At the request of either party, the parties shall promptly
execute and record, at the cost of the requesting party, a short form memorandum
describing the Premises and stating this Lease's Term, its Commencement and
Expiration Dates, and other information the parties agree to include.

13.10  Survival of Remedies.  The parties' remedies shall survive the expiration
or termination of this Lease when caused by the Default of the other party.

13.11  Authority of Parties.  Each party warrants that it is authorized to enter
into the Lease, that the person signing on its behalf is duly authorized to
execute the Lease, and that no other signatures are necessary.

13.12  Business Days.  Business day means Monday through Friday inclusive,
excluding holidays identified at Section 6.02(b).  Throughout this Lease,
wherever "days" are used the term shall refer to calendar days.  Wherever the
term "business days" is used the term shall refer to business days.

13.13  Entire Agreement.  This Lease contains the entire agreement between the
parties about the Premises and Building.  Except for the Rules for which Section
12.01(a) controls, this Lease shall be modified only by a writing signed by both
parties.

13.14  Definition of Lease.  This Lease consists of the following:

     (a)  Title Page;

     (b)  Table of Contents;

     (c)  Articles I through XIII;

                                      -31-
<PAGE>
 
     (d)  Signature Page;

     (e)  Rider containing Option To Extend

     (f)  Exhibits A through E.

     (g)  Addendum I - space and Rental Allocation Summary


     IN WITNESS WHEREOF, the parties hereto have duly executed this Lease the
day and year first above written.


LANDLORD:           MILKSON ASSOCIATES, INC.

                    SIGNATURE:

                    /s/ [signature illegible]
                    -------------------------

                    DATE:  5/5/97

WITNESS             NAME:  /s/ [signature illegible]

                    TITLE:

                    DATE:  5/5/97
                          -------

TENANT:             ACCIPITER, INC.

                    SIGNATURE:

                    /s/ [signature illegible]
                    -------------------------

                    DATE: 4/29/97
                          -------

WITNESS:            NAME: /s/ Catherine L. Bearden
                          -------------------------

                    TITLE:

                    DATE: 4/30/97
                          -------

                                      -32-
<PAGE>
 
                                   EXHIBIT A

                                  [Floor Plan]

                                      -33-
<PAGE>
 
                                   EXHIBIT B

                                   [BUILDING]

                                      -34-
<PAGE>
 
                                   EXHIBIT C

                                     [LAND]

                                      -35-
<PAGE>
 
                                   EXHIBIT D
                             LANDLORD IMPROVEMENTS

Landlord shall paint and carpet the suite in colors selected by Tenant and 
approved by Landlord. Other modifications to the suite will include the 
relocation of doors and walls as located on the floor plan below. Landlord shall
provide double wood doors at the suite entrance. The expense of any 
modifications and/or additions to this plan shall be borne by Tenant.

                                      -36-
<PAGE>
 
                                   EXHIBIT E
                             RULES AND REGULATIONS

(1)  Access to Common Areas of the Property.  Landlord may from time to time
     establish security controls for the purpose of regulating access to the
     common areas of the property.  Tenant shall abide by all such security
     regulations so established and agrees to always leave clear access for
     vehicular traffic through all parking lots, loading areas and driveways.

(2)  Protecting Demised Premises.  Before leaving the Demised Premises
     unattended, Tenant shall close and securely lock all doors or other means
     of entry to the Demised Premises.

(3)  Building Directories.  The directories of the building shall be used
     exclusively for the display of the name and location of tenants only and
     will be provided at the expense of Landlord.  Any company names and/or name
     changes requested by Tenant to be displayed in the directories must be
     approved by Landlord and, if approved, will be provided at the sole expense
     of Tenant.

(4)  Large Articles.  Furniture, freight and other large or heavy articles may
     be brought into the building in a manner so as to not damage the property
     and always at Tenant's sole responsibility.  All damage done to the
     building, its furnishings, fixtures or equipment by moving or maintaining
     such furniture, freight or articles shall be repaired at the expense of
     Tenant.

(5)  Signs.  Tenant shall not paint, display, inscribe, maintain or affix any
     sign, placard, picture, advertisement, name, notice, lettering or direction
     on any part of the outside or inside of the building, or on any part of the
     inside of the Demised Premises which can be seen from the outside of the
     Demised Premises, without the written consent of Landlord, and then only
     such name or names or matter and in such color, size, style, character and
     material as shall be first approved by Landlord in writing.  Landlord
     reserves the right to remove at Tenant's expense all matter other than that
     above provided for without notice to Tenant.

(6)  Compliance with Laws.  Tenant shall comply with all applicable laws,
     ordinances, governmental orders or regulations and applicable orders or
     directions from any public office or body having jurisdiction, whether now
     existing or hereinafter enacted with respect to the Demised Premises and
     the use or occupancy thereof.  Tenant shall not make or permit any use of
     the 

                                      -37-
<PAGE>
 
     Demised Premises which directly or indirectly is forbidden by law,
     ordinance, governmental regulations or order or direction of applicable
     public authority, or which may be dangerous to person or property.

(7)  Hazardous Materials.  Tenant shall not use or permit to be brought into the
     Demised Premises or the building any flammable oils or fluids, or any
     explosive or other articles deemed hazardous to persons or property, or do
     or permit to be done any act or thing which will invalidate or which if
     brought in would be in conflict with any insurance policy covering the
     building or its operation, or the Demised Premises, or any part of either,
     and will not do or permit to be done anything in or upon the Demised
     Premises, or bring or keep anything therein, which shall not comply with
     all rules, orders, regulations or requirements of any organization,
     bureaus, department or body having jurisdiction with respect thereto (and
     Tenant shall at all times comply with all such rules, orders, regulations
     or requirements), or which shall increase the rate of insurance on the
     building, its appurtenances, contents or operation.

(8)  Defacing Demised Premises and Overloading.  Tenant shall not place anything
     or allow anything to be placed in the Demised Premises near the glass or
     any door, partition, wall or window which may be unsightly from outside the
     Demised Premises.  Tenant shall not place or permit to be placed any
     article of any kind on any window ledge or on the exterior walls; blinds,
     shades, awnings or other forms of inside or outside window ventilators or
     similar devices shall not be placed in or about the outside windows in the
     Demised Premises except to the extent that the character, shape, color
     material and make thereof is approved by Landlord.  Tenant shall not do any
     painting or decorating in the Demised Premises or install any floor
     coverings in the Demised Premises or make, paint, cut or drill into, or in
     any way deface any part of the Demised Premises or building without in each
     instance obtaining the prior written consent of Landlord.  Tenant shall not
     overload any floor or part thereof in the Demised Premises, or any facility
     in the building or any public corridors or elevators therein by bringing in
     or removing any large or heavy articles and, Landlord may direct and
     control the location of safes, files, and all other heavy articles and, if
     considered necessary by Landlord, require supplementary supports at
     Tenant's expense of such material and dimensions necessary to properly
     distribute the weight.

(9)  Obstruction of Public Areas.  Tenant shall not, whether temporarily,
     accidentally or otherwise, allow anything to remain in, place or store
     anything in, or obstruct in any way, any sidewalk, court, passageway,
     entrance, or shipping area.  Tenant shall lend its full cooperation to keep
     such areas free from all obstruction and in a clean and sightly condition,
     and move all supplies, furniture and equipment as soon as received directly
     to the Demised Premises, and shall move all such items, and waste (other
     than waste 

                                      -38-
<PAGE>
 
     customarily removed by building employees) that are at any time being taken
     from the Demised Premises directly to the areas designated for disposal.
     All courts, passageways, entrances, exits, elevators, escalators,
     stairways, corridors, halls and roofs are not for the use of the general,
     public and Landlord shall in all cases retain the right to control and
     prevent access thereto by all persons whose presence in the judgment of
     Landlord shall be prejudicial to the safety, character, reputation and
     interest of the building and its tenants provided, however, that nothing
     herein contained shall be construed to prevent such access to persons with
     whom Tenant deals within the normal course of Tenant's business unless such
     persons are engaged in illegal activities.

(10) Additional Locks.  Tenant shall not attach or permit to be attached
     additional locks or similar devices to any door or widow, change any
     existing locks or the mechanism thereof, or make or permit to be made any
     keys for any door other than those provided by Landlord.  Upon termination
     of this lease or of Tenant's possession, Tenant shall surrender all keys to
     the Demised Premises. Tenant shall be solely responsible for the costs of
     all locks and keys other than the original set in the premises as of the
     date of occupancy.

(11) Communications or Utility Connections.  If Tenant desires signal, alarm or
     other utility or similar service connections installed or changed, Tenant
     may install or change the same without the approval of Landlord, but at
     Tenant's expense.  Tenant shall not install in the Demised Premises any
     equipment which requires a substantial amount of electrical current without
     the advance written consent of Landlord.  Tenant shall ascertain from
     Landlord the maximum amount of load or demand for or use of electrical
     current which can safely be permitted in the Demised Premises, taking into
     account the capacity of the electric wiring in the building and the Demised
     Premises, taking into account the capacity of the electric wiring in the
     building and the Demised Premises and the needs of other tenants in the
     building, and shall not in any event connect a greater load than that which
     is safe.

(12) Office of the Building.  Service requirements of Tenant will be attended to
     only upon application at the office of Anthony & Co. Employees of Landlord
     shall not perform any work outside of their duties unless under special
     instructions from Landlord.

(13) Restrooms.  The restrooms, toilets, urinals, vanities and the other
     apparatus shall not be used for any purpose other than that for which they
     were constructed and no foreign substance of any kind whatsoever shall be
     thrown therein and the expense of any breakage, stoppage or damage
     resulting from the violation of this rule shall be borne by Tenant who, or
     whose employees or invitees, shall have caused it.

                                      -39-
<PAGE>
 
(14) Intoxication.  Landlord reserves the right to exclude or expel from the
     building any person who, in the judgment of Landlord, is intoxicated or
     under the influence of liquor or drugs, or who shall in any manner do any
     act in violation of any of the rules and regulations of the building.

(15) Nuisances and Certain Other Prohibited Uses.  Tenant shall not (a) install
     or operate any internal combustion engine, boiler, machinery,
     refrigerating, heating or air conditioning apparatus in or about the
     Demised Premises; (b) engage in any mechanical business, utilize any
     article or thing, or engage in any service in or about the Demised Premises
     or building, except those ordinarily embraced within the permitted use of
     the Demised Premises specified in, Article 7; (c) use the Demised Premises
     for housing, lodging, or sleeping purposes; (d) place any antennae on the
     roof or on or in any part of the inside or outside of the building other
     than the inside of the Demised Premises, or place a musical or sound
     producing instrument or device inside or outside the Demised Premises which
     may be heard outside the Demised Premises; (e) use any illumination or
     power for the operation of any equipment or device other than electricity;
     (f) operate any electrical device from which may emanate electrical waves
     which may interfere with or impair radio or television broadcasting or
     reception from or in the building or elsewhere; (g) bring or permit to be
     in the building complex any bicycle or other vehicle, or dog (except in the
     company of a blind person) or other animal or bird; (h) make or permit any
     objectionable noise or odor to emanate from the Demised Premises; (i)
     disturb, solicit or canvass any occupant of the building; (j) do anything
     in or about the Demised Premises tending to create or maintain a nuisance
     or do any act tending to injure the reputation of the building.

(16) Solicitation.  Tenant shall not make any room-to-room canvass to solicit
     business from other tenants in the building and shall not exhibit, sell or
     offer to sell, use, rent or exchange any products or services in or from
     the Demised Premises unless ordinarily embraced within the Tenant's use of
     the Demised Premises specified herein and specific authority granted in the
     lease agreement.

(17) Energy Conservation.  Tenant shall not waste electricity, water, heat or
     air conditioning and agrees to cooperate fully with Landlord to assure the
     most effective operation of the building's heating and air conditioning,
     and shall not allow the adjustment (except by Landlord's authorized
     building personnel) or any controls.

(18) Building Security.  Upon entry to or exit from the building the exterior
     building doors and suite entry door(s) should be kept locked at all times
     to assist in security.  The janitorial service (if any) shall, upon
     completion of its 

                                      -40-
<PAGE>
 
     duties, lock all building doors. Problems in building and suite security
     should be directed to Anthony & Co.

(19) Parking.  Parking is in designated parking areas only.  There should be no
     vehicles in "no parking" zones, or at curbs.  Handicapped spaces are for
     handicapped persons and the Police Department will ticket unauthorized
     (unidentified) cars in handicapped spaces.  No vehicles may be abandoned or
     repaired on the property, and vehicles requiring extended parking should be
     identified to Landlord.

(20) Janitorial Service.  Tenants will remove excessive trash from inside and
     outside their premises and shall deposit same in the dumpsters provided by
     Landlord.  Any large volume of trash resulting from delivery of furniture,
     equipment, etc., should be removed by the delivery company, Tenant, or
     Landlord at Tenant's expense.  Any requests for extraordinary trash removal
     should be directed to Anthony & Co. at 832-1110.

(21) Landlord reserves the right to make such other reasonable Rules and
     Regulations as in its judgment may from time to time be needed for the
     safety, care and cleanliness of the Building and the Land, and for the
     preservation of good order therein.

                                      -41-