Vista "Run As" Not working

[TitaniumZX]

Does anyone know how to get the "Run As" to work on Vista? I'm trying to run some of the 2003 support tools (AD Users and Computer, DNS, etc) with my domain admin account and it's not working. When I do a Shift+Right Click>Run As it never prompts me for my username/password. I do this in XP and it works like a champ. Thanks.