I have Googled the error in an attempt to help but it doesn`t look good I`m afraid. All I found from MS was click here which shows that it is (I think) a corrupt key. My search click here shows a lot of people have experienced this but nobody seems to have a satisfactory answer.
Perhaps someone here has fathomed out a solution.
For the future, the registration key is in WINDOWS/system32 and is file wpa.dbl. I keep a copy on a floppy in case this sort of situation occurs. It saves the need for re-registration.
Hope this helps.