System Stalls & have to reboot

Hi, hope someone can help. My system spec hopefully will appear in my sig if I've done it correctly

Had an ongoing problem for months with pc stalling if I try to use media players or run some games. I have enabled windows error reporting and it comes back saying that it is driver related. I have updated drivers, but think it may be related to the Nvidia driver, I have the latest one. I can start a movie or game but it will crash the system after a short time.

I have so far replaced the power system, the cpu fan and heat sink (as pc seems to over heat too) I put system into local shop and the guy checked it and said hardware was all ok, he too thinks its a software/driver issue.

I used a few different driver detection software to update drivers, any ideas guys? this is puzzling a few people who have looked at it

Cheers

Jan