To RHochstenbach: thanks for all your help I tried driver cleaners but it still gave me blue screen also, but even though it said dxgkrnl.sys on the blue screen, I did try underclocking my CPU as I had an Athlon 64 3000 at 2.4ghz with a stock fan where the stock speed is 1.8ghz so i thought it may have been a little too high, I set it to 2.0ghz and haven't had the blue screen since I last posted, it seems a bit wierd as it has nothing to do with directx, maybe it isn't the solution as the blue screen did happen randomly, but I'm happy for now lol I have tried updating all drivers, unplugging all usb devices and none of those worked, so MAYBE this is it, but what confuses me is it was displaying a driver message on the blue screen which has nothing to do with CPU, and also I didn't get any blue screens on any other CPU intensive programs- I am pretty sure I haven't changed anything else other than the CPU speed, unless the driver cleaner has worked and it just took a few restarts to get rid of the blue screen? Clearly I am no pro and I appreciate all the help, but I wish there was a definate reason if possible as I'm now worried about changing any settings whatsoever in case it starts happening again- I want to be able to overclock my GPU etc but I'm scared to touch anything now its working it seems very unpredictable, does Vista have any logs that I can show anybody? I tried the error reporting thing in control panel and it just said "there was a problem with a device driver that caused a blue screen" nothing else... I just want a stable system, sorry again if I'm being unclear or if it seems like I'm repeating myself, I have just tried all the driver side of things and had no luck until I changed the CPU clock speed, which doesn't "appear" to be the problem but has somehow solved it (for quite a while now, never had BSOD since)