Windows 7: Black screen w/cursor just before CTL+ALT+DEL prompt

Greetings,

I have a Windows 7/64 on a dual Xeon box (Dell Precision 470).

There was a group policy that rolled onto my machine and caused the computer to no longer display the login. It was a DCOM restriction that shut everything down on this box. The AD server is Win2003/32 (no SP).

Anyhow, because of the locally cached machine policy, the friggin PC will stall just before the CTL+ALT+DEL displays (with the pretty little dove and sh!t). The screen goes black and my cursor is the only thing that works. If I press C+A+D again, the pretty little dove comes up for a few seconds, then goes black.

ANyhow, I can't get into the system using F8/F12 or the Windows 7 DVD repair util - that shows a Problem Signature of "noRootCause".

I can still see files on the drive if I hook it up elsewhere. Is there any tool or way to get the local machine policy off of the machine and force it to come in clean again without reformatting?

Many many thanks.