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Tech Corner

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: 

  1. Right click on the “My Computer” icon on your desktop and choose “Properties” (If you have been clever enough to do away with Microsoft’s “My Computer” you can find the System Properties by going: Start/Settings/Control Panel and choosing the “System” icon) Or . . . easier yet; while holding the 'Windows' key down, tap the 'Pause/Break' key.
  2. On the System Properties page that opens, select the “Hardware” Tab and click the “Device Manager” button
  4. Once the “Device Manager” dialog is displayed, open the “Mice and other pointing devices”. It should show several different mice or pointing devices and you are looking for the one that you don’t have - probably a Ballpoint mouse and maybe a Serial mouse - right click the offender and choose “Properties”
  6. At the bottom of the properties box that appears, will be a “Device usage” drop down list - select the “Do not use this device (disable)” choice. The mouse that you have disabled will now appear on the Device Manager list with a red X across it and you should have no more problems.
  7. 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.

Jon, N7IGG