Group Policy Results Wizard - RPC server unavailable to Win7 client

[disturbedone]

When running 'Group Policy Results Wizard' from a W2K8R2 server (or Win7 client) to a Win7SP1 client I get the error

Failed to connect to DOMAIN\COMPUTER due to the error listed below. Ensure that the Windows Management Instrumentation (WMI) service is enabled on the target computer, and consult the event log of the target computer for further details. Details: The RPC server is unavailable.

The error is pretty unhelpful. On the Win7 client I've checked the WMI service is started (also the RPC service is started) and the event logs show nothing at all.

I've seen this error before on a WinXP client (see

http://www.tek-tips.com/viewthread.cfm?qid=1695388).

I would get the error if the firewall was on but not if it was off. It ended up being one little typo in the firewall GPO. The best thing was that turning the firewall off got it to work so that proved it to something in the firewall config. The problem here is that turning the firewall off does not allow GPRW to work.

Any ideas why Win7 gives this error and how to resolve it so GPRW will work?