Adding the sims 3 exe file to the exceptions list for DEP helps prevent crashes. Here's a step-by-step that may help you:
https://simmetrydesign.forumotion.com/t90-is-your-sims-3-crashing-check-this
If you play sims off-line, that helps prevent crashing too.
For me, I watch the compositor caches. When the compositor cache rises close to 100k or the simcompositor cache gets close to 500k, then I know I need to use "save as" and then quit.
Also, if saving is taking a long time, that is clue to check those compositor caches.
Possibly your system was vista and then updated. I'm not a computer techie, so this is all I can offer!
