trouble authorising with a new harddrive

My computer harddrive died and i lost all content. I have reinstalled Digital Editions with no problems. However, when i tried to authorise it, so that i could transfer my epub files to my ereader, i got the error message : you can only authorise this computer with an Adobe ID that hasn't previously been used to authorise any other computer or mobile devices. Please try again."

I assume this is because with the new harddrive it is recognising the computer as a new one? Or maybe it is something else entirely, i am not very good with computers...

does anyone know how to fix this?