I had an issue where i installed Windows Virtual PC to test some software.

I created a standard windows 7 professional virtual PC from our network image added to the domain etc just as if it was a physical PC.

I installed the software to test and it worked under my domain admin account.

When I tried to login to the virtual machine as a test student account it kept saying ""the requested session access is denied"

I tried all sorts - before I realized the fix.

Log in to the virtual PC and bring up system properties.
On the remote tab click the bottom option "Select Users"
I added our domain users to the list and hey presto I could log in as a test user

just sharing my experience...