Windows 7: Windows Anytime Upgrade to Pro Fail

Okay so I am a college student. I bought a windows anytime upgrade key for Home Premium to Professional. I need it for the classes I am taking. Only when I enter the product key it validates then I press upgrade and a few seconds later it says it was unsuccessful. Following that it says that my key doesn't work for windows anytime upgrade and to enter a different code. The key is specifically for upgrading through windows anytime upgrade from Home Premium to Professional. I am quite frustrated

Nevermind. I went to restart my computer to try again, and it started upgrading. After I ran dxdiag to make sure it is now Windows Professional...

I've just had the same symptoms - bought a machine with HP installed and an "anytime upgrade" to Ultimate. Got the same stupid message.

Restarted and now it's saying it's updating.

Considering that it costs 95 quid to upgrade, you'd think it would work flawlessly, wouldn't you?

I'll let you know if it succeeds.

Update: it's now saying "Windows 7 Ultimate" on the screen, but it's still doing updates....