Most companies have a policy against storing personal data or programs on company computers. Your laptop may, someday, unexpectedly require service. The computer support staff can't really take the time to safeguard your personal files. If your laptop is the only place you're storing last year's tax records or your child's homework, you may be in trouble. Never allow friends or family members to use your business laptop.
Small indiscretions can sometimes lead to big problems.
For example, if your laptop is stolen from you, management probably will not hold you accountable. If, however, your laptop is stolen from your spouse, who only borrowed it to do the family Christmas newsletter, management may not be so understanding.