1. Go to Control Panel/System/Advanced/Performance Settings.
2. Go to the Data Execution Prevention tab. Click on "Turn on DEP for all programs and services except those I select" and press "Add." You will now add your Sims game, expansions and Stuff Packs to the DEP exception list. Copy-and-paste these "C:" locations in the spot where it says "File Name."
Sims 3 base game:
C:\Program Files\Electronic Arts\The Sims 3\Game\Bin\TS3.exe