mouse-problem on p200mmx-board

i have installed a serial logitech-pilot-mouse on com1-port. i could see the recognition as logitech-pilot-mouse. in device-manager was a serial plus ps/2-mouse.without exclamation mark. mouse was working. but then i changed the mouse and not only this second one but other logitech-mice(like the working one but not the same type)were not recognized. i have deleted both entries with and without safe mode. in safe mode any mouse was working. i was told i will have to delete an inf-file. which one?