Well David it sounds like the mouse plug may be the culprit. Check the plug and make sure nothing is caved in. If you have another USB mouse squeeking around try it. If not you may want to go to your nearest animal shelter and get a new one.
and life goes on...
p.s. I'm really sorry. I just couldn't resist!
Recently, my mouse began to frequently require that I relocate its plug from its current usb port to another. IOW, I often start up or reboot my desktop PC to find no mouse pointer until I move the mouse plug to a different port.
Its only a standard 2-key scrolling-wheel usb mouse and my desktop has 2 onboard usb 2.0 ports and a 4-port usb 2.0 pci card. The mouse seems to work ok with all 6 of these ports, but must often be switched over from 1 port to another.
BTW, my PC is a home-built desktop with an AMD Athlon XP 2200+ and 2GB DDR RAM, and my OS is Win2K-Pro that runs on NTFS format.