Splinter Cell Double Agent needs help

I used to run SCDA on my Vista, but it used to raise my processor's
temperature into critical, and my computer would shut down. To handel this
problem, I got a new cooler for my processor and mainboard, but ever since,
when I try to run the game, it opens the menu, lets me load a saved game,
and then suddenly stops responding. I tried lowering graphics and
resolution, disabling AERO, etc. , but still nothing. I know my system can
handel the game, because I used to be able to play, so I'm helpless about
the problem...

Please help! (Thank's in advance)