Sims 3 crashes after 10 minutes into game

I got the Sims 3 last year, and the first couple of times it worked perfectly for hours, but then it started to crash about 10 minutes into the game. A message box pops up and says something like "Sims 3 has stopped working because of an un-known error.." every single time! And i am forced to shut down or restart my computer. i have a dell laptop with windows 7. i tried the thing where you add the Sims to the DEP list or whatever, but it didn't work. i don't really want to have to download a program to fix it, I'm just wondering if there is anything i can do!
someone help!!!!!!!