I had this problem when I was swapping out hard drives between linux and ms (I have those removable drives you swap out from the front of the case).

Anyway, 2 things:

1.  You should call them and get a new reactivation number

2.  If they refuse you, dispute the purchase with your cc company and buy a new copy elsewhere.

They ARE crossing the line legally and so they typically give you a new activation # no matter what.

Ciao,
              George