First that catches my eye is that you both have a 32 bit operating system.
A 32 bit system can only allocate 2 GB of RAM to a program at the most. The Sims 3 is very inefficiently programed and needs a lot of RAM. That is a problem but usually it shouldn't crash the game in CAS. Crashes after 2-4 hours and save error 12 are much more likely to be a RAM issue.
The Sims 3 is an absolute graphic hog and the more EPs you add, the more strain it puts on the cards. The open neighborhood needs a lot of rendering so despite popular believe, the Sims 3 is not a simple game that doesn't have high specs. Also, the game is inefficiently programed, there's no denying that. CAS is also very heavy on the graphic that is why many are seeing crashing issues on lower-end cards.
Now your daugthers graphic canrd has an whole other issue: The card does not handle heat very well (see this: http://simswiki.info/wiki.php?title=Game_Help:TS3_System_Requirements). Now with all the issues this game has, that might be the problem she's running into. It might be worth to run a program that monitors the heat to see if it goes to far up.
Your card should be ok with just Supernatural installed but your drivers are from June last year. Are you certain there aren't any newer ones ?
Also are you also seeing crashing while playing the game or is it just in CAS ?
My suggestions for the moment:
- Monitor the heat, especially on your daughters computer. If the temperature indeed does get high, it might be time for a new graphic card (suggestion can be derived from the link I gave above)
- Turn off mirror reflections in the game options
- Turn down the graphic options in the game options
- Check on the fps (to do so, open the cheat console with ctl-shift-c and type fps on. Check the number in the upper right corner - I think it's that corner). Shouldn't be higher than 100
I hope that any of these suggestions help you out a bit, if not, feel free to post back.