Windows Explorer Encountered an Error

My mother-in-laws computer got some kind of virus. I think it was antivirus scareware. It prevented me from opening any antivirus software, any .exe files, opening IE, task manager, control panel etc.

I was finally able to remove some viruses but not all of them because i still couldn’t do anything. I used the CD that came with the computer to reinstall window xp with service pack 1. *I have also downloaded the remaing critical updates as well as service pack 2 and 3 from windows.

I downloaded avast last week. I ran it however after i did so i began experiencing problems with windows explorer. I thought it was just part of the virus so i uninstalled avast and reinstalled System Mechanic Professional. It found 60+ trojan files.

Is it possible that avast flagged clean microsoft files as viruses causing the new installation to be corrupt? Is there a way to find out if i am missing key microsoft files or if i still have viruses on my mother-in-laws PC?

Welcome cmschapp

Windows XP SP1 is very very old and should be updated to SP3 that has been available for over a year.

I am sorry i didn’t make my self clear. I have installed service pack 2 and 3 along with all other critical updates available from microsoft.