Computor thinks the serial
adaptor supplying NMEA
is the mouse, hence random movement.
Boot the computer first with mouse attached, then plug
in usb to serial adaptor.
Follow the script. ie new device detected.
Did he supply a driver? If not search the net for a driver for the adaptor.
Alternatively go to System/hardware/device manager and check the serial to usb appears on a port.
What OS are you using? Also google
crazy mouse & get a more detailed description
of what I related.