I used the update to go from 5.1 to 6.0 on my XP-SP3 PC and my Win7 notebook. The notebook had no trouble. The XP totally locked up. Avast would not let Task Manager come up. I tried uninstalling in safe mode and then reinstalling with the setup file (from CNET). I tried again with(a slightly larger file) downloaded directly from Avast. Still no luck.

Whenever I uninstalled, I also blew away the files in the programs directory and checked for trash in the registry (using TweakNow). I tried to go back to 5.1 and the virus datafile update would not work. Finally found a link in the downloads for the file to manually update the Avast 5.1. After wasting Saturday PM and Sunday. I have my XP PC back… I hope. :cry:

If you have XP maybe you will be lucky, or maybe you’ll go through Hell. You might be wise to wait for an update to 6.0 before you upgrade an XP machine.

–Luckydog