Re: The Sims 3 (with Showtime expansion) constantly freezes and crashes

This first link is a nifty chart that shows you how well your Graphics card would fare with certain expansions. Your card falls into the "Maybe" category with Showtime. http://simswiki.info/wiki.php?title=Game_Help:TS3_System_Requirements

This second link is a little more in-depth with Showtime requirements, which shows that you fall a tad short when it comes to processing power, but you seem to be okay on everything else.
http://help.ea.com/en/article/what-are-the-system-requirements-for-the-sims-3-showtime/

As far as the Code 12 error goes, are you running Windows 7 32-bit or 64-bit?