I recently bought an XFX 250 GTS graphics card for my all-stock Dell Dimension 9100 Computer. I also bought an Antec 500 watt power supply upgrade, and they are both successfully installed in my computer. However, whenever i go to play a game such as WoW or call of duty WaW, the game freezes up about every 20 minutes and then i have to restart my computer. Now i know this is not an overheating problem of the card, but what could the cause of this problem be? Any Solutions?