I'm using a really old DOS app (which I purchased years ago) for my business. However, the hard drive on which it is installed is dying and I would like to transfer it to a virtual PC. The existing PC runs Windows *8. If I try to simply copy the files from one PC to another, it pops up a message asking for a code and stating that it's not authorised. I have tried cloning the hard disk, but with the same problems. I have swapped out all other hardware components (MB/CPU etc) with no issues. I have also copied the entire program directory and renamed the original; this worked fine. Finally, I tried to edit a VMWare machine to have the same hard disk serial as the original. This didn't seem to work either. I'm now totally stuck! Does anyone have any thoughts how this app knows when it's not on the original hard drive and how I could get around this?