When you uninstalled TC, did you do a 'full' removal or just use windows, sometimes things are left behind.
Three things come to mind, either something gone screwy in the registry, or, Windows has sent out an update which messed things up, like a recent windows 10 update that crashed quite a few computers (though I understand your using windows 7).
Or, you need to do an almost 'full' uninstall (without registry stuff). Uninstall TC, go to This Post
, to where it says 'clean install'.
But - also go to Documents (or My Documents) - TurboCAD 16, copy everything in there (AutoSaves, backups etc.) into a new folder somewhere on the computer so you have a copy of everything, then delete the whole folder TurboCAD 16 folder, if TC re-installs OK, you could copy things back if necessary.
Try a re-install, There have been reports of UAC (windows user account) settings messing things up. but I'd try the above first as I haven't personally had any problem with UAC.