I still remember when I was using the RC bit of Windows 7 Ultimate, I had problem loading the Devices and Printers option, where it takes forever to load and remains blank. Then I kept searching in many forums but seems not much people had this problem, and no one could provide a solution but one day I foun this post from snappydog:

Really weird, when selecting Devices and Printers (Device Stage) in the menu the progress bar would take forever and never display anything – just blank.

Finally discovered it was actually a bluetooth issue in services. I don’t even know why I looked there – –

THE FIX at least for me..

Click Start button, type “services” into the search program and files box. This brings up a list in the menu, select Services. This should open a list of local services on your system.., Find ‘Bluetooth Service” and make sure it has started, right click and set to ‘automatic’ (mine was already set), Select “Bluetooth Support Service” and start, set to automatic (mine was set on manual) —

This fixed my issue, hopefully yours as well..

So, yup, it definitely fixed my problem, and I repost it in several Windows 7 forum and it did helped some people as well, so hopefully you see this if you facing this problem and pulling your hair.