Hi! geordiejohn1950, welcome to 7F
As a test have you tried shutting down
your machine then log onto the Windows OS, and check if the sound is okay?
There is a possibility that Ubuntu is not properly releasing the resources of the sound card after a restart from Ubuntu.
It would help to know what version of Ubuntu you are running.
You could also try running the 'Playing Audio' troubleshooter while you are in Windows in:
Control Panel\All Control Panel Items\Troubleshooting