Unable to do the DEP for the sims 3?

Just like alot of other people, my sims game has been crashing to the desktop. I have the base game and late night expansion and ever since I downloaded the new path and installed late night on my computer, I have't been able to get p the intro video and the launcher for the game is not working properly. I read that I should try turning off the DEP for the sims 3 but I can't find the TS3.exe file because there is no bin file. I have no custom content installed and no mods. I run windows vista. What can I do?