Problem fixed on this particular model if you press the rest on the keynote pad beside the + - key at the same time as the rest button it wil place you keyboard on mute. I find no reference to this in any manual and I think it is just a programming glitch (but a scary one if it happens it you) by repushing the rest &+ buttons at the same time it allows you workstation to return to normal.

Thank You both for you help it really helped, by the way the Casio 1200 manual st tat sight is missing the last page 'Troubleshooting' it is where I got my present manual.

Thanks Again!!!!