Missing mouse

Thanks for your explanation about NVKeystone. As I don't use projectors or Micrsoft PowerPoint I don't know how I obtained this program, but it does not tell me why my mouse freezes in the first place, some times after using the computer for an hour or so.
(It may have started after I downloaded Windows Office Vista beta a few months ago)

If you don't use NVKeystone, you may want to uninstall it. That can be done by clicking uninstall under NVKeystone listed under Programs on the Start menu; or under Add/Remove programs in the Control Panel. If it isn't listed there, it may be part of another program. You may be able to find it by using Search. Remember to uninstall the program-- don't delete it. Deleting it could cause a number of problems.

I am afraid that if I find and uninstall NVKeystone, if my mouse still freezes the only way to retrieve it will be to reset the computer.
Having to do this all the time will be a pest.
I am not worried about NVKeystone. Only constantly losing my mouse!!