I had a similar prob, but this may not have anything to do with yours, as you can play other games, basically 6600+ cards, think all 6 series, not sure, need extra power, so having the mimimum psu requirments(think about 350watt) is essential, otherwise you get a message that says your gpu isn't running at full power, which causes games, like in the case i had quake 3 to quit out after a short period of time. Basically, theres a molex connector on the end of your card, connect a free molex cable, like the one you'd connect to your dvd drive ect from your psu, into the 6600's one. That increases the power it recieves, it's actually necessary if you have a low watt psu ect. Anyway it sorted my prob out, as i only had a 350 watt. Just make sure you cards installed correctly, ect, and check and update the cards drivers as term mentioned, if needed, hope this helps.