We found another solution while deploying Windows 7 that we could not find information anywhere on the internet. Our client wanted an aggressive power management strategy for their desktop computers; that is they would be forced to try and save power across their fleet of client, desktop computers.
When building the systems, we found that the Windows 7 Aero interface wouldn't work. We also couldn't run winsat (the experience index calculation tool) from either the command line, nor the control panel.
After searching through tons of blog entries and support forum requests, we found the problem in our own log. The power settings couldn't be applied - and winsat exited with some other error from WMI indicating that an instance of an object could not be created.
After turning off the GPO, everything started to work again.