Windows 7: cannot get my bluetooth headset working

I tried to connect my old Motorola H500 via a BT dongle to my new ASUS laptop K52F with Windows 7 home premium, It pairs fine although I am not asked for the passkey code (0000) as I was used to under XP. The earphone is shown in the device list and also when I right click on the BT icon in the task bar it shows the earphone as the only BT device.
But I can neither hear anything nor use the mike.
To make sure it is on, I set it to predetermined/default in sound control. When I play a piece of music with the mediaplayer I can see the volume bars in this sound settings window go up and down but I cannot hear anything.
When I use it with skype and test mike and voice, no sound from the mike is detected and the test sound cannot be heard.

I played with all possible settings but there does not seem to be a way to make it work.

Anybody has an idea?
BTW, no services are reported for the device.

I read several related threads (non exactly the same) but it seems that the problem is in Win 7. Someone said that it worked fine after a clean reinstall. I cannot do that because the OS was preinstalled and there is no disk.