TurboCAD 12 wont run since update

I've got a group of users who are all running TurboCAD 12 on a managed
operating environment.  They all installed an update and they all
updated ok except for one computer.  Now, since the update, when he
clicks on the TurboCAD icon or selects it from the menu, nothing
happens.  No errors, but the program just will not start.

I've tried uninstalling and reinstalling but it makes no difference so
the corruption must stay resident on the computer itself despite the
reinstallation.

Any ideas?