The title states the GPU I use. Yeah, it's AGP, my computer is old 
I've found that this game has been crashing lately, for some reason that I could not discern. The only thing I could link to it was the fan noise changing pitch when the game would freeze (and once when it used up my entire pagefile and made the computer adjust it to be larger (hasn't happened again)!). I took a peek, and no, my computer/gpu/etc was not overheating.
After poking around in Ntune a bit, I found the controls for the onboard fan. I realized it was set to automatically adjust itself to minimize noise when extra rpm wasnt needed. It tended to automatically bounce between 50% and 79% when playing this game, and every crash coincided with it ramping up to the 79%. I have a 550 watt powersupply, which should be ample for my computer, as it's from 2004... a P4 2.8ghz running on Windows XP, nothing that special or hoggish.
Anyway, point in case, I took direct control of the fan, and set it just to run at 85% (constantly). It kept the temperature fine, even in the middle of large battles and what have you. Also, it has yet to crash like it did before - and I've put in a lot of hours the last couple days. And yes, the game runs fine on my computer, the only adjustment I've really had to make is to turn off the "Debris" option.
Anyway, this isnt really an answer to anything... but I have been hearing of alot of Nvidia crashes - my drivers are "169.21". I dunno... maybe the auto control of the fan is fubar and causes some sort of hiccup or something (beats me, I'm not a techy)? Meh, it's someting to give a shot... who knows, maybe it will stop your crashes too? It's easy to try, and easy to set back to automatic when you're done playing SINS. Good luck, all.