Sims 3 Crashing Entire Computer!

I've been experiencing crashing with my Sims 3 game while playing. It causes the entire computer to shut off.

I've tried the following:

I've reinstalled several times with no change.
I've completely updated the game and even downloaded the Super patch thing I found on the EA help site with no change.
I've been sure to disable DEP for the game and the two installed expansions, Seasons and Generations, with no change.
I've altered by processing power to 100% while plugged in with no change.
I've updated my graphics driver software with no change.
I've cleared my cache and have been playing in windowed mode.

I'm pretty sure that my computer meets the minimum game requirements. I used to play the game with these two expansions often, but took a break and uninstalled. I reinstalled a few days ago and these problems began.

The crashing does not seem to corrospond to any specific aspect of game play.

I am sure to turn off any background processes I can that may overclock the computer.

Any idea what is going on or how I can fix it?