Hello Kloppstock, try uninstalling the mouse completely, re-boot your PC and run through the hardware detection process.

You could also try using the original drivers first and see if it works, if not do the same thing again but use the latest drivers.

Run a disk check, and a virus/spyware scan in safe mode, and think about when the problem started and wether there were any recent changes that you made to your PC prior to when the problem began.

What type of connection has the mouse got i.e. ps/2, usb, serial?

Regards

Martin