Mark: I have hesitated for a long time to send this, but I am sure that by now you realize there is NO solution to this problem and it has NOTHING to do with your Mouse installation or drivers or whatever anymore than checking to see if the sun is shining or it is raining outside when this happens. Microsoft has to know why this is happening and that it is not solvable but they are not telling us all the facts that they must be aware of. In my case I have tried everything that anyone has come up with in this forum and none of them work. On the other hand, there are a few times that I have come back to my computer and by some miracle the screen saver is on and working!!!!! I have tried to pin down what was running at that time, but just trying to find the cause made the screen saver go off and I could not get it back again.
So, I think we all have to sit back and recognize that we are NOT going to be successful beating our heads against a brick wall. It is sort of like if you don't like the way the electric power comes to your house you should change power companies only to find out that the one you are using has a monopoly franchise for your area. Just the way that the Microsoft monitors to this forum respond to our comments are a clue to how much importance is given to these forums. They just push a button to the closest canned response that may cover something and that is what you get- nothing.