SPDIF output stops working when audacity is run

[usernameaudacity]

I normally have audio output through the computers optical SPDIF output. This normally works, however when i start audacity the SPDIF output stops working (i say stops working, in so far as the device connected to the computers optical out looses the signal, so this could be either the signal isnt present or its being output in an incompatible format for the device receiving it) but in any case from that point the SPDIF out dosent work (ie no sound on the pc comes out at all) even after audacity is closed, until i restart windows and it comes back.

Any help would be much appreciated.