I now have this same problem. I can launch FTM 2012 in another (new) user (not synced or even registered). I have deleted the FTM folder within the Temp folder (of the main user's Documents and settings folder). Still the program won't launch from the main user I had.
I am out of town and do not have access to my original cd to reinstall the program.
Ancestry should allow us to download the program again if we previously purchased this (I did when the program was released, before the download version was available).