It looks like Windows does not always identify the device as a mouse. It may depend on what signals are being sent at the time. I only figured it out because I was installing an XP VM on the machine and noticed the new hardware pop-up that mentioned Microsoft Serial Ballpoint Mouse then immediate cursor control loss. This had not happened in the several years that the setup had been in place. It could have to do with a Microsoft Update. When this originally happened, I noticed that when I returned to pick up the machine, the cursor was working fine with no user intervention. After a restart the problem reoccurred. With the new Windows 7 machine we installed, the issue happened after a restart from the VMWare Player installation, but a restart remedied the problem and the driver was not showing in the Device Manager. It is certainly odd and I won't be able to research the exact reason for the problem. I just know that it is intermittent and will resolve itself just as randomly as it occurs.