The 'Play windows start up sound' is checked in the sound section in control panel.
When I select a .wav file from the programme box and press test, no sound is heard. However if navigate to the sound wav in Windows>media folder and select the sound and open it in media player, the sound plays fine. Its as if the sound section in the control panel has lost where to open files and I can't work out how to link that programme to the relevant one to play the sounds. However, it's not really a problem, just curiously annoying that I can't figure it out. There's probably some sort of codec missing somewhere, but what.... Never mind. Thanks for your help.