Berber I know this is off PhilG's topic but I had similar problems instead it was with my WiFi card.
I resorted to shutting down and restarting but I just could not let it stop nagging me that it was not working as it should.
It turns out that Windows 7 has a selective suspend setting for USB.
Just go to your advanced power setting and you can change the USB suspend settings so that the Bluetooth device does not completely loose power when the computer hibernates.
Once that is done, your Bluetooth device should resume from suspend or hibernation.
Just my 2 cents though