parallels 8 won't launch Window 7 after using Mac Migration Assistant

I upgrade from an older Mac mini to a newer model and used Mac's Migration Assistant. There were some minor hitches but the biggest is when I installed Parallels DT 8 for Mac it can't get Windows 7 to launch. As a matter of fact, I can't even see Windows 7 program. I tried reinstalling Windows 7 but it stopped with an error message. Lost as how to proceed. Windows 7 was an upgrade from Windows XP and worked fine on the old mini using Parallels DT 7. Should I uninstall all Windows and Parallel programs and reinstall?