Got Logon to System - Activation Issues

Vista Ultimate Beta 2 was installed as an upgrade to Windows XP Pro SP2.
After the installation went fairly smooth I logged into the box. Upon login,
the system said:

A change occurred to your Windows license.
You must re-enter you Vista Ultimate product key to activate.

Then there is a box for the product key and a cancel button.

No matter what key I put into the system (I have the one on the CD case
label, as well as MSDN) it does not give me an OK or Update button.
Therefore the only option is to select cancel which then logs me back out.

There are no errors given or anything else to assist troubleshooting. I am
able to login to Safe Mode with no options, but I get a similar error if I
login to Safe Mode with Networking. It is as though it is requiring
activation before showing a desktop.

How do I get around this? I know my keys are 100% valid and have never been
used on other machines.