Very recently my computer has been randomly freezing on me. It usually happens when I start light multitasking, at first the main window I am using freezes and if I alt-tab to another program it freezes, then my entire explorer.exe freezes and I cannot enter task manager. My mouse cursor moves perfectly fine though. If I turn on my computer and don't do anything however, it does not freeze at all no matter how long I leave it on.
I have run prime95 to check my cpu, memtest86+ to check my RAM , HDD diagnostics tools and defragmentation, checked the temp of my 8800GT evga video card (55C, I don't know of any programs to diagnose the video card), my motherboard is a DFI Lanparty P35-LT and has a little LED on it that says FF (fully functional) so I don't think its a hardware problem. All temperatures for the other computer components were also within standard levels. I have also scanned for viruses using kaspersky, adaware, spybot, malwarebytes, superantispyware, and conficker scanners and they found nothing.
Could the problem be due to an error in the Windows registry? I noticed my computer started freezing after I tried extracting a rar (perfectly safe contents as I have extracted it onto another computer for use) and this would have put my hdd space down to 400mb on a 1tb hdd, which had 83% fragmentation (yea I defragged, but it didn't fix the problem). Any ideas?
RAM: 2x2gig G.Skill ddr2 800
GPU: Nvidia 8800GT
Mobo: DFI Lanparty P35-LT
HDD: 1tb Western Digital Caviar Green
OS: Windows XP SP3