I think that you have two devices that are interfering with one another. You may, as Maptech suggests get away with disabling the touchpad -- or

I'd suggest that you unplug the GPS, open the Device Manager then plug the GPS in. You should see the USB device or, if it's coming in as something else, whatever was addeded when you plug it in.

You may be able to change the Com port that you're using manually to avoid the conflict -- if that's it.

You then would take your Offshore Navigator and make that Com port your GPS source.