sambuckies Have you tried uninstalling and reinstalling .NET Framework 3.5 again? The Sims 3 errors in your dxdiag look like .NET errors, so it's worth reinstalling even if you did so in the recent past.
In case you don't remember how (or someone else is reading this): Click Windows key-R, enter appwiz.cpl in the run box, click "Turn Windows features on or off," and you'll see .NET 3.5 near the top of the list. Check the filled-in box to uninstall it, and restart your computer. Repeat the process, except clicking the now-empty box to reinstall, and restart.
If that doesn't help, please look for new errors in the Reliability Monitor. Click Windows key-R and enter perfmon /rel in the run box, and you'll see a chart of errors and updates with a column for each day. Today is on the right.
Look for an error that happened at exactly the time you tried to launch Sims 3 most recently. If you find one, click "Show technical details," copy the details, and paste them into a post here. If you don't see anything, check back in an hour or so; the Reliability Monitor doesn't always update right away.
