Uncontrollable Cursor Behavior with Windows XP and a Serial GPS Input
At some point if you are using Windows XP, your computer has multiple serial (COM) ports and one or more of those serial ports is connected to a GPS which is providing NMEA data, you are ripe for problems. At best, the cursor will ricochet around the display uncontrollably until the GPS is unplugged, and worse case it can damage the XP load to the point that a reformat and reload is necessary. I've experienced both.
The problem is an XP glitch that recognizes the GPS NMEA input as a Ballpoint or Serial Mouse and every time the GPS sends an NMEA data sentence, which continuously occurs, the cursor will do a fast lap of the display. Just about the time you think you have it corralled, off it goes again. Usually, the problem appears when the GPS is providing data and the navigation program that uses that data is not open. If the Nav program is open and ready for the GPS data, things will normally be fine and no problems occur.
There are a couple fixes, one only is good until you start the computer again, and the other should be good indefinitely. Both involve using the Windows Device Manager and are reasonably simple to do. In the temporary fix, you simply uninstall the offending mouse and everything will work until you start up again and Windows will dutifully reinstall it. The permanent fix is to tell Windows not to use it again.
For either fix, you will have to wait until it occurs and the cursor goes nuts, unplug the GPS to get control of the cursor - Then:
In case you thought I was clever enough to figure this out, forget it. Some kind soul on the Sunday Tech Net started me in the right direction with the temporary fix and the real hero is Dave Leone of Voyager Systems in Ft Lauderdale. Dave's Company specializes in marine electronics and computing solutions and he was kind enough to e-mail me the fix which I have passed on here.