Well I did e-mail customer support and received a response. I detailed the problem, including the issue of it being the sync files, not the software itself, per se. The person who responded agreed the sync files and user configuration files seem to be corrupt and recommended a manual uninstall of the software.
This link was provided and does provide some useful information about the location of files/registrations: http://ancestry.custhelp.com/app/answers/detail/a_id/4848
, especially those in the registry.
When I launched FTM in the newly-created user name, I tried to download my original (linked) tree from ancestry, but the action column showed nothing could be done. After playing with a test file, I found I could unlink the tree and it would allow me to download it again from ancestry.
The very first link in the manual uninstall is the key to removing those configuration files (see: http://ancestry.custhelp.com/app/answers/detail/a_id/5029/se...
After deleting these files, my program launched great!! From there it is a process of re-registering the program and restoring/re-linking or transferring files.
I did not remove the software at all.
Thanks for all your help. I hope the above helps someone who might have this issue. Sorry for the rambling.