Icue installed? Firmware up to date? I have been using the headset every day for several months and it always works...
P.S.: Try a different USB port for the receiver...

Thank you for your answers. I was able to solve it now, it was an error in the Icue software. Strange, but now it works again.

How did you connect it with cable or with the slipstream dongel? I am not sure if the dongel works on a receiver.