N68-S - Windows 7 - No audio output device is installed

[edave]

I have upgraded my pc from windows xp to windows 7 32bit and the sound has stopped working.
The speaker icon on the task bar reports that "No audio output device is installed"
I have loaded the latest nvidia motherboard drivers from ASRock and the Realtek HD audio drivers and it is still not working.

Any suggestions welcomed, thanks.

Dave