New Security Mechanism? or MSFU?

I am setting up a new test system for my technician to use. It is a Windows 2003 server and two Windows XP Pro systems. We used our license from MSDN and the weird thing is it wanted them registered, we call microsoft, got the code and then restarted, when the system came up it says you need to activate this copy of windows, click OK, it says it is activated and restarts. Log in and it says you need to activate this copy of windows, click OK, it says it is activated and restarts. (repeat the process). I can't get into my system.....

Is this a way Microsoft says FU with a special key?

I reinstalled, called and the same thing happened again. I used a code off of my other systems and then called and the system worked. That is why I inquired about the MSFU.