Street Fighter 4 for the PC seems very unstable for me. It is constantly quitting itself and I have had my disconnect rate go to 8%.
I tried upgrading my video drivers but surprisingly it made things worse than better. Prior to the upgrade I could play at 1600 by 1200, now I must choose 800 by 600.
8600GT is a bit old now but it should be enough to handle SF4, especially if you’re playing at a lower resolution. I had an 8800GS and got 59.92 FPS at 1080p resolution, SF4 is not incredibly demanding.
Anyway, to the OP: Mine used to crash too. Did you use the character unlocker hack? I had once-a-day crashes earlier on, then after using the character unlocker it started doing it much more often. I then uninstalled SF4, deleted the folder, and reinstalled and it’s been working perfectly ever since.