VaniBrunner 42b86c2824de1b5e Please try playing in a clean user folder. Move the entire Sims 3 folder out of Documents > Electronic Arts and onto your desktop. When you launch the game, a clean folder will spawn with no content. (Your saves and other content will be intact in the folder you've moved but temporarily unread by the game.) Don't add anything to the new folder yet; just start a new save and see how it runs.
If you get another crash, please provide a dxdiag. Click Windows key-R, enter dxdiag in the run box, wait for the scan to finish, click "Save all information," and save the file to your desktop. From there, you can attach it to a reply using the paper clip (Attachment) icon included with the other formatting buttons.
TuniPuni1 Error 12 is an out of resources condition, usually but not always due to the game going over the RAM limit. (This limit is the game's not your computer's, at least most of the time.) How much memory is Sims 3 using when you first load it? What about after you've been playing for an hour or so? You can check in the Task Manager. Put the game into windowed mode, but don't minimize it.
Please also let me know how much RAM your computer has overall.