Well I had a thought, as editing with WPCREDIT / WPCRSET didn't help I went and installed Real player & let it take over all sounds.
Before this trying to play a CD produced an error, it would not even start playing with Media Player.
Now CD's play and you can listen to them with the output jack on the front of the cd player, no errors are produced.
I still get an error trying to play WAV files or MP3 files though, now it says the device is already in use.