If no other changes were made to the computer, and the QCT was not updated, obsolete or not, the software should work. I would re-load the software on a different computer and run it in simulation mode, or connect it (the other computer) to the quilting set up for a test run. If it works when the other computer is hooked up, that most likely means that either the original computer has a problem or the QCT software is corrupted, or both.