The problem you have is a corrupt Virus definition file that was downloaded with Live Update. You are not the only one with this problem of late. Follow the steps provided from the Symantec site from the link in the previous post.
Then this is only a suggestion, uninstall Norton Anti Virus as it is more trouble than what it is worth, then either download AVG 6 from
www.grisoft.com (this software is free) it is just as good if not better than Nortons. You can also obtain AVG 6 from PC Essntials magazine and then you only have to download the latest definition files. This program also has a automatic update feature.
All my customer's computers I have loaded this Anti-Virus software on have had no problems with Viruses. It picked up the "Bug Bear, Code Red, Klez, I love You" viruses and many more days before Nortons did.
[Edited on 16-12-2002 by haugmichael]
