I recently purchased a new desktop (DUAL core 2.13GHz, 2GB RAM, NVIDIA 8500GT) and whenever I play games such as Bioshock and Half Life 2 everything runs smoothly for about 10 minutes before it slows down big time and I have to restart the game to make it PLAYABLE once again. I've played around with the texture detail and resolution which doesn't seem to fix the problem. Any help?How good is the cooling in your computer? It might be overheating.
Does this happen at the same time every time?Yeah I would also say heats issue; you’re probably talking CPU or video cards fans...

1- Check your fans run smooth
2- Check they don’t stop all together
3- Check for Blockage
4- Does this happen when PLAYING older games
5- Does this happen when watching something such as a video file?
yeah i think you may be right there. i doubt there's anything wrong with the fans themselves but the cavity in my DESK where my computer sits GETS pretty hot sometimes. i'll try taking it out and see if that fixes the problem. thanks a lot for your help guys.Opening one side of the case helps a lot as well.