A little tip:
I ran into an issue today with my Windows 7.
I don´t know if it had anything to do with me buying a new mouse this past weekend but suddenly when I tried to open the “devices and printers” dialogue but the progress bar would take forever and never display anything – just empty.
I searched around for it on the web and got some suggestions pointing me towards the “Bluetooth Support Service”. So, I set that service to start automatically and…well now it works again!