Can't activate after new motherboard
I have Windows 7 Home Premium 64bit.
Recently my PC died, and was diagnosed as needing a new motherboard, which I now have. Windows had to be re-installed, but when I try to enter my product key from the sticker on the DVD case, it comes up "Invalid character" when I try to enter the 4th from last character (which is definitely an "8").
What do I do please?