Sorry, I didn't see your edit until now. Sims 3 doesn't require any compatibility mode, and using one often causes more problems than it solves. Please undo the setting and let me know whether the game launches. If it doesn't, please move your entire Sims 3 user data folder out of Documents\Electronic Arts and onto your desktop, and let the game spawn another clean folder, at least for now. There might be a corrupt file preventing the game from launching, or it might be something else, and this is the fastest way to find out.
If the game still doesn't launch properly, please run a dxdiag. Hit Windows key-R, enter "dxdiag" without quotes, wait for the scan to finish, click "Save all information," and save the dxdiag to your desktop. Upload it to a filesharing site (the free version of pastebin.com is fine), and link it here.
