We just had our new computer built and now we're having some issues. We have a 500g (C) and a 250g (D) harddrive, Asus M4A78-EM motherboard, 2g Ram, Modxstream-Pro power supply (700W), and a GeForce GTS 250 video card (PCI express 2.0 512MB GDDR3). With Windows 7 Pro 64-bit OS. When we play games like Sims 3 and Warhammer Online the system crashes between 5 mins to an hour or so. The screen goes black and acts like the computer has shut down but the fans go full speed and the power light is still on. We took it back to our builder and he ran tests and stressed it with it never happening at his store. He told us it was not an overheating issue but we're not sure and he's not exactly helping. There are 2 fans (1 on the processor itself) and those we can feel are still blowing cool air and there is no warning when it happens the screen just goes black. It is clean of dust and debris, has at least 6 inches above and beside the case and since we live in the South the A/C is on just about 24/7). We have not had this problem when just browsing the internet or when it's idle (turned on but no one is using it). Both of these games worked properly on our old XP PC but since we've brought this computer home we can't use it for what we bought it for. We did install Steam for one of my husband's games but we have not had an issue with that game crashing, I had heard rumors that Steam caused system crashes. There is very little installed on this computer and it is only 1-2 months old. No overclocking or anything is done. It is strictly a internet browsing and gaming computer. We have tried lowering our resolutions and still had the issue. Any help is greatly appreciated! We spent a lot of money on this machine and we want it to work properly.