When I try and add a new computer in AD, once I have entered the computer name I can only press ok which then adds the computer but doesn't allow me to enter the Mac address/GUID. My colleague can do this on his computer though as once he has entered the computer name he can go to next and enter the Mac address/GUID.

Does anyone know why this is, it would be great if I could get this working on my computer. I'm running Windows 7 so I thought this could be the cause but I had also tried on our XP computer in the server room and it does the same!

I'm sure I have the full admin pack installed.