Why has my antivirus client stopped working after I did an upgrade install of Windows Vista?

If you have performed an upgrade install of Windows Vista from a previous version of Windows and you did not remove your antivirus software before the upgrade, you will likely experience many problems with it afterward.

This is especially true when upgrading to Vista while having Symantec AntiVirus CE 10.1.5.5000 or earlier installed. Doing this will cause the antivirus client to stop functioning, and you will be unable to reinstall it or another client. The only working solution at this time is to do a clean reinstall of Windows Vista.

To ensure this does not happen, completely remove your antivirus client prior to performing the upgrade. For help with removing the software, see In Windows, how do I uninstall programs?

Also see:

• For Symantec products at IU, where can I find help online?
• In Windows, how do I safely upgrade to the latest Symantec Endpoint or AntiVirus software?
• Can I use Symantec AntiVirus or Ghost with Windows Vista?
• Known issues with Windows Vista at IU
• How do I install Windows Vista?