Mustek 1200 problem reinstalling

My sister has a Dell 4600, 2 yrs old. we've been going through major problems with it freezing and going offline, months of issues with dell ( I think she got a lemon) Its been non funcioning half the time for over 6 months. It is working now and we were trying to reinstall the mustek software and can't seem to get it to work, she is able to scan with her HP all in one.
Dell had us set the computer back to its original settings, empty I did not think we would have to uninstall and reinstall.
Any ideas where we went wrong?
Lyn