I can think of a couple of things.
#1 It's folding as a service.
#2 It's running from your startup menu.
#3 Your Machine ID's need changing, run using the -config flag.
Do a CTL/ALT/DEL and see what you have running and check under Admin tools that you don't have it running as a service.
I don't know at what point the previous unit was but I suggest you clean out the folding folder and reinstall the folding client.
Yes, that should fix it, but you'll lose any work in progress.