So a couple months ago my game has started crashing shortly after loading a save. I can play for minute or two, then game crashes to desktop with message "The Sims 3 has stopped working" (or something similiar, I don't have English software). There is no freezing (by freezing I mean unability to play together with all the background sounds, branches moving and so on) and game doesn't crash when it gets through these hard first minutes. Sometimes I can reload the game and everything is just fine, sometimes it's the same error. And sometimes I can load a game, play for hours and nothing bad is happening...

I can't figure out what's the reason. Normally I don't have much free time, so I don't play on regular (or even daily) basis, but last week I was sick and stuck at home and I wanted to play...one day everything was fine, the next day it wasn't. I can't see any particular circumstances (e.g. overheated computer, new EP or CC) that would be common for these crashes.

According to Wikia, my computer is strong enough. This is a new laptop, I bought it in December. I have Ambitions, Late Night, Generations, Pets, Supernatural, Seasons, University and Island Paradise. No SPs.

I've tried:
- deleting cache files
- removing CC and putting it in back in game piece by piece
- renaming game folders to "start fresh"
- doing DEP tweaks
- deleting saves or going back to previous ones - in case one of them was corrupted
When I encountered the problem at the first time I found out that I have two graphic cards - one integrated, the other one being GeForce 720M 2 GB. I switched to the second one and it seemed to fix the problem, until now.
Everything from above seemed to help, but just for a while - even with new game folder: I made a new family, move them into a house, played for a few hours and exit game...aaand I can't play them anymore.

Should I reinstall the game? If so, what's wrong?

I have crash logs from today and previous weeks, I can post them here if there is a need.
Also I'm really sorry for possible grammar or spelling mistakes - English isn't my mother tongue.

Are you sure you are using the dedicated graphics instead of the integrated one? See this post - http://www.modthesims.info/showthread.php?t=481768

Yes, I'm positive. Even now I have my game minimalised and I can see this little colorful tray icon next to te clock. Also DeviceConfig.txt says so:

since you did try with new user files, were you able to start a new game and play or did it still crash? Trying to determine if this is only on saved games or new games and without any package or sims3pack files installed.