just an update.
I called Apple tech support and after a few special restarts everything is running normally again.
First I had to start-up in safe mode (holding Shift at the dong)
Then restart without logging in. I had to plug in a standard usb mouse to be able to click the restart button.
After starting back up the usb mouse worked fine, but the bluetooth Mighty Mouse still couldn't click, so I had to shut down again and restart while holding Option -

- P - R until hearing three start-up dongs.
Everything works fine now.....not really sure what it did but I have to say that I'm pleased with Apple's tech support.
🙂