BleepingComputer.com: Frequent total crashes

My problem is that Vista won't run for more than a couple of minutes before fatally crashing. I might be surfing on Firefox or using Word, and all of a sudden it doesn't respond to clicks anymore, and everything stays immobile. The only thing I have left to do is force a shut down by pressing the power button.

Sometimes it's able to show the desktop while it's in that that state, but that's all it can do. I can't even access the task manager, and if I'm lucky enough reach the start menu to have it restart, it won't obey the command.

I've tried virus scanning with AVG but it crashes halfway. SpyBot crashes halfway as well. Even Combofix crashed halfway too! (while attempting to create the log file). Running AVG in safe mode works fine but it says I'm virus free. I've done a defragmentation succesfully in safe mode, but it hasn't solved the problem.

What can I do now?

Your help is much appreciated,

Ariel.

Running Vista Home Premium on
Intel Core 2 Duo Processor
3 GB Memory
250 GB Hard disk drive (only 30GB free)

first thing i would do is test your hard drive and memory. (just to be safe) then i would start looking at using the system restore feature and try to restore your computer to a time before it was crashing.

Thanks quantumtsunami.

Which tool would you recommend for testing the hard drive and memory? Should I run it in safe mode?

Could this problem come from anywhere else?

the ram maybe tested thought the bios the hd could be tested with the vista disk
did the computer work fine for awhile before this started happening?
is you cpu fan working at over 1200 rpm is the heat sink clean
if all above is good i would upgrade the ide or sata interface drivers as well as flash the bios. also try down clocking you ram to the lowest setting and see if that helps