Computer Freezing, help requested

Hey, today my computer has frozen twice, within 20 minutes of eachother. before today it would freeze once or twice a month or even less so I never worried about it when it happened. I have not installed anything new, and have 25 out of 298 GB of free space.

system specks are:
Windows Vista home premium, 32 bit
2GB ram
intel core 2 quad cpu Q6600
NVIDIA GeForce 8800 GTS 512
NFORCE 680i LT SLI

when it happened I only had firefox and a Microsoft office document open. During the freeze i have to push the reset button the case, nothing else works. I use spybot and kaspersky, according to those scans im pretty much virus and malware free.

Could this be a software problem with windows? maybe some of my hardware is failing? thanks for any help in advance.

 

Have you run through the spyware cleaning section? Here

 

I have not. I didn't think it was necessary because running a spybot scan or kaspersky scan shows no infections.

 

Even thought spybot shows nothing, the other software may find something.
If you run throught and get confirmed that your clean then come back,