I'm cleaning my hd before I'll upgrade to Windows10.

I had two earlier versions of Netobject Fusion but I deleted them yesterday from drive C.

Today when I try to open my NOF15, it says always this:

"The serial number entered for this installation is invalid. Please obtain the serial number from your registeration card and reinstall or contact customer service."

Does this really mean, that I have to reinstall NOF15 now? How about my old sites?

My NOF is in drive D if that matters.