For some days I had the following issue on my Windows 7 installation: clicking on the start orb then on Devices and Printers would open the window, show a progress bar and then nothing else, a completely empty folder.
I tried a restore that didn’t solved the issue but it reminded me that I installed some days ago a Bluetooth software for a Bluetooth headset I received as a Microsoft MVP gift. This gave me the direction to search for.
I ended up seeing in the Services that the “Bluetooth Support Service” was stopped and that it Statup type was set to disabled. Re-enabling it fixed my issue and now I have again the full list of Devices and Printers shown in the dialog.