Okay, uninstall the game and whatever EP/SPs you have. Clean out the registry before you do a new install and go to Sims 3 Programs to download the separate updates up to 3.0.x and install them yourself. Then go into the Launcher and disable the autoupdate feature.
Try that method and see if that will work for you. My game is updated to 3.x.x. I was about to update when I saw Madcat256's comment about the latest patch at Simbology in the Sims 3 section. If he didn't warn us, I would have had the same issue too.
MAKE SURE that you save your game saves and your mods to their own folders on the desktop that you can access. The site does give you thorough instructions saving your mods and game saves before you update the game by hand.
I forgot to include a link for you to go and download the individual updates for Sims 3:
Sims 3This has several patches going up to 1.10.6.004017
World AdventuresThis has several updates going up to 2.4.004017.
High End Loft Stuff*This has two patches going from 3.0.004001 to 3.1.004001 and from 3.0.004017 to 3.1.004017
My latest game version is 3.1.004001. I haven't updated to the latest patch.
The above will give you the updates you need to update by hand. Go up to 3.1.004001 and stop there. Test to see if your game will run at that point. Let us know how that works for you.