More information related to Cookies is published on the FAQ pages. The only way to fix it, is upgrading to a version, preferably those released after 1999. Each certification authority will apply their own policy. More information on the validity period is explained by Netscape . Finally, this is fixed with Microsoft latest MAC version.
More information is available on The Netscape Unofficial FAQ .
The same may apply for Outlook Express if it does not install correctly. More info on this subject, you may get from MacFixIt . If you have problems signing in on HotMail with Expolorer 4.x then you better upgrade to version 5.x. The security certificates may no longer be supported. The proxy settings may work fine for Web access but may conflict with your mail client.