I am not certain if this is from a virus or a hardware issue, but I noticed this problem after cleaning up a virus infestation. It was a sizable infestation so I suspect I may still be infected with things unrelated to this symptom despite scanning my system with Avast and several adware detectors. Whenever I switch desktops with the fast-switching method and attempt to use windows explorer to view folders, explorer.exe crashes. Under these conditions internet explorer will not open, probably crashing soon after initialization. I recently (yesterday) reinstalled my OS using my new SATA hard drive as the system disk. The infection probably came from a file downloaded into the temporary internet files. This issue was occuring at odd times in the previous installation, but I was never able to get the explorer crashes to happen at will. The issue just crept up if the computer was left running long enough. It was part of the reason I reinstalled. Now it crashes the same way as before, but under specific circumstances. (I have not yet left the system running for a long period of time, so the other part of this issue may still exist) When these explorer crashes occur, the desktop reappears quickly and applications that are still running (werent closed by the explorer crash) reappear. I can still view folders within programs' file open dialogs. I have no idea what is causing this

You still have to rule out the virus aspect and take things one step at a time. Boot to safe mode than do a virus scan. I would also suggest using a free online scan of a separate virus program such as trend micro http://housecall.trendmicro.com/ You will have to turn off your system restore as well because if you clear the virus and leave restore on, than you are keeping the virus in restore backups. You should also be using a pro-active malware protection program such as spywareblaster which runs in background to prevent loading spyware. Using layered protection for malware is needed, not just one program that will not work. You may need to download HJT (Hijack this) and than go to either http://www.castlecops.com/forums.html where they can assist you on reading the HJT log file and ridding you of problems or register at http://www.smartestcomputing.us.com/ and you can get assistance on cleaning up the security problems.

I do have a multilayered defense I have spywareblaster, spywareguard, spybot S&D, Avast antivirus, ad aware SE.