I installed AVAST last night after running Kapersky online scanner. I allowed Avast to reboot and run a scan at which time it found 4 virus infections and deleted them. When Windows finished loading, Avast was immediately deleted. When I click the desktop icon is tells me the file is not found and the icons that reside in the tray are gone. I had been using Avira AntiVir PersonalEdition Classic and it detects a trojan in my local settings/temp folder called perflib perfdata. This may be a false indication according to Google searches. Either way, there is definitely something deleting Avast and I am hoping to not have to do a complete format and re-install of WINXP.
Looks like you had a rootkit on your system before installation.
See http://forum.avast.com/index.php?topic=26554.0
http://forum.avast.com/index.php?topic=25941.0
- BlackLight - It can detect rootkits like Rootkit Revealer but can also remove them. http://www.f-secure.com/blacklight/try_blacklight.html
- Panda Rootkit Cleaner - http://research.pandasoftware.com/blogs/research/archive/2006/12/14/Rootkit-cleaner.aspx
Also see, anti-rootkit, detection, removal & protection http://www.antirootkit.com/software/index.htm.
david none of them removed my root problems only the fsecure blacklight is renaming them and giving you a log file so you can manually remove them. but anyway i renamed those files but since it was on hided folders i didnt have any access to them or i never had any information about what filename they was renamed to.
and the panda anti root is only removing the root viruses but dosent remove other important files that is reinstalling the root viruses back on.
And to clean all the registry entries i had to use another program again since it wouldnt both of the above didnt help with that so i had to get registry booster.
I think we need more efective anti rootkits out here since none of them can help a newbie.
Anyhow and my own problems isnt solved yet i managed to delete all the viruses but it seams like it made enough damage so now i cannot load windows up in the safe mode no matter what i do, i get blue screen critical error and reboot 
snakie, you should post this in the original topic so that everything is together, http://forum.avast.com/index.php?topic=26889.0 so any of the others who help on the forums can see all the information relating to the problem and you aren’t hijacking another topic.
You can try a visit to the antirootkit.com site and see what other information or tools are available.