Got a strange one here, I'm hoping someone might be able to help, can't get anything out of Apple

We have about 60 Intel iMacs, in various forms, connected to our Active Directory Network.

All users log in to the domain using their Active Directory accounts, are have their work areas mapped at log in.

This has worked without fault for 2 years.

We have just installed the lasted "Mac OS X Update Combined 10.6.7" on a few of the iMacs. After applying this update the users no longer get the mapped drive to their work area.

It is definately something that has happened after this update, as if a user logs onto an iMac that hasn't been updated, they get their works areas as normal?

Any advice would be appreciated, I'm starting to pull my hair out