Well. At least 17 is working right. I'm open to suggestions. Mike.
What Operating System and Version are you using? (e.g.: Windows 7; Windows 8 )
Did you try "Run as Administrator"? (right-click on TurboCAD-18 icon, and click on "Run as Administrator")
Do you have installed the latest/greatest/last Build/Update/Hot-Fix
of TurboCAD-18 installed? (go to Updates and Patches Forum for version-18 here
I'm no expert-guy... but those are the things I would check and try.