If you can launch FTM from another Windows account, then the problem is not with the installation of FTM, and there should be no reason to reinstall. For Vista and later users of Windows, sync files are stored in your user profile (i.e., Windows user account) under c:\users\...\appdata\roaming\familytreemaker. To synchronize your tree from a different Windows account, you have to copy these files over.
If the program won't launch from one of your user accounts, then my guess is the fault is in one of the files that is stored in the account or its registry settings, or otherwise it wouldn't work with a different account.
The question is which file, files, registry settings have gotten messed up. I don't know the answer. I suggest someone with this problem exhaustively search through the registry settings to find out if something is stored there that could be causing this issue.
Unfortunately, the help desk is incapable of helping with this problem. Things would be a lot easier if we had one of the developer's mindshare for a few moments.