I have a laptop. Every time it booted, Windows 7 popped up an error message stating that the hard drive had reported a fault and that it should be backed up.
I cloned the drive using Norton Ghost to a new hard drive (I couldn't use Windows Back Up to do it because the new drive is a smaller SSD and it wouldn't allow me to restore the image) but now Windows claims that it's not genuine. I've definitely typed in the correct product code from the label on the bottom of the laptop.
I tried following the Windows 7 steps shown here http://support.microsoft.com/kb/950929 but activating online fails and redirects me to a page to buy a new copy of Windows and I don't get given the option to activate by phone as shown in their screen shot.
I still have the old hard drive (so long as it doesn't fail) if that helps.