Hi erod49, try looking in your error logs. You have given a good discription of the problem. Tel us your system specs as well.
To get into your error logs,
Left Click on Start Menu.
Right click on Computer and choose manage.
Click on the event viewer.
You now have loads of options to try and pin down what is happening.
Expand the error tab.
Look for things in the last 24 hours.
Other things to look for are updates, has an update caused this. Has your computer autoupdated any of the motherboard drivers
Have you tried to restore the computer before the error started or has it always been like that.