Bluetooth Audio cuts out after 2 or 3 secs

Hi

I Have a Dell desktop with a Belkin USB Bluetooth Adapter (Widcomm Driver
4.0.1.2401) paired with a Plantronics Voyager 510 Headset and a Motorola
phone.

The headset works fine with the phone.
I can transfer files (photos) from PC to phone OK.
When I play audio or speech from PC to headset it plays for about 3 secs
then cuts out if I switch headset off and on again I get another 3 secs.

Someone suggested it could be XP's speech recognition taking over so I have
followed the instructions for removing that although some of the files and
the Registry entry was not there.

Any ideas anyone?

Thanks