Explorer.exe error no desktop

I have an HP Pavilion 515x with 756 MB ram, 240GB HDDs (and 40 and a 200), and running Windows XP Home Edition (a version made BEFORE any of the SP updates, which I do have now). The other day, Wednesday I think, windows did an update and had an error in a program called "Peer Gaurdian." When I woke up the next day the computer brought up my desktop wallpaper but then gave me an explorer.exe error. I booted into Safe Mode and ran Adaware (it found something called Alexis), Registry Repair Wizard, Ewido, AVG Antivirus, and uninstalled Peer Guardian. None of these worked so I checked and windows told me to disconnect and logoff the user in the task manager, and then to reboot. This works but I have to do it every time i want to get on besides using Safe Mode (the error doesn't occur in Safe Mode). I don't know what to do right now. I tried restoring to an earlier time and it got so bad I couldn't do anything but use Safe Mode, so i undid the restore.