Sunroof "Booming" noise

First time the weather has been good enough to open the sunroof since I had my new E320CDi Wagon last September.

Starting at about 20mph and becoming worse as i go faster, I get a "booming" noise that oscillates at an increasing frequency. Actually get painful at 40 + mph.

If I partly close the sunroof the intensity falls. If I slightly open my window it goes away.

Anyone else suffer from this problem ???

Regards

Mike