I played the whole of half life 2 with no issues, half life episode one for the most part with no issues. Until i was at the end of the game, my computer screen would randomly go black and this repeating sound came from the speakers. Making me force shutdown my computer every time.
Ever since then i can only play 10-20 mins of episode one or two before this event happens again. after experimenting with other games i've come to find out that it even happens when playing torchlight.
apart from your graphics card being horribly under powered to run well anything above solitaire you might be having heat issues or power issues. check and see if your case is hot inside. if it is you may need better cooling. If not post the rest of your system specs (hard drive, cd rom, how much stuff youve got plugged into it via usb, whether or not you have a pci sound card or nic or modem or anything like that, etc. and I can tell you what power supply you'll need to be running to be able to play without lockups.
All that being said you might want to invest in a higher end gpu as well. hell you can get a gts450 for ~100 bucks on newegg (galaxy currently has a MIR for theirs making it 75 bucks)
thanks for your responce.. I think its a problem with overheating because i touched the graphics card when the issue happened again and it was damn hot that i had to withdraw my hand.. So i was wondering if you could suggest a better cooling unit (thats relatively cheap) im also planning to change the graphics card to the one you suggested,