Crazy Mouse
by LarryH on 02-Jul-2011

I installed a Serial Gear 4 port serial to USB converter which runs a FTDI chipset. Link:

The device is sturdy, in a metal case that can be screw mounted, and performs well, EXCEPT for generating a 'crazy mouse' when plugged in. It doesn't always cause the problem, but sometimes I have to plug and unplug the USB connector several times to get it working. Best results when plugging in the USB connector are when CE is running, and all the serial devices (AIS, GPS, Auto Pilot) are already running.

Is there a permanent fix?

Larry H Currently cruising SE Alaska

03-Jul-2011 RBEmerson

Weird. I use the same 4-port box and haven't had a problem. Why are you unplugging and plugging in the adapter as often as it seems from your note?

03-Jul-2011 LarryH

The computer is a laptop and I have to set it up for each days use. The computer sits over the companionway to the v-berth area. My procedure is to place the computer, then plug in the power, then the USB for the mouse and Rose Point GPS. Then I power up the computer, open CE, turn on the other GPS, auto pilot, and AIS radio. (All on the Serial Gear box) Then plug in the Serial Gear box's USB connector. Mostly the computer recognizes all the equipment, but sometimes it must think one of the Serial Gear inputs is a mouse, resulting in 'crazy mouse'. The only solution I know is to then unplug the Serial Gear USB cable, wait, then plug it in again. The mouse action is normal until I plug in the Serial Gear connector. Any other start up procedure seems to make the problem worse. Plugging in without the Serial Gear's equipment already running always results in 'crazy mouse'.

03-Jul-2011 Rose Point Staff Member brad

The FTDI driver adds some options to the Windows Device Manager that you can adjust to disable mouse detection.

I don't recall the exact name of the option, or where to get to it, but the procedure is something like this:

Open the Device Manager, expand the Communication Ports list, right-click on a COM Port and select Properties.

Look for a button labeled Advanced (I think) and click it.

In the new window, look for an option labeled Skip Enumerations and check it.

Repeat this for each FTDI based COM port...

07-Jul-2011 d_meister

If that doesn't work out for you,both Nobeltec and The Capn have fixes. Here's Nobeltec's:

"Erratic mouse behavior is typically a symptom of Microsoft Windows misinterpreting NMEA data on a serial port as mouse movement. To resolve this problem, follow the steps below. Start with the computer turned off and the GPS turned on and connected. Turn on the computer and let the mouse go crazy for about 2 minutes (5 minutes in Windows 7). Then turn off the GPS. Click on Windows Start menu and right-click on My Computer/Computer. Select Manage. On the left side of the Computer Management window, click on "Device Manager." Once the list of devices appears, click on the + next to "Mice and other pointing devices." Right-click on "Microsoft Serial Ball Point" and select Disable. Click "Yes" to the next message that appears.

You may then close the Device Manager and turn the GPS unit back on."

The Capn's can be found at:

07-Jul-2011 LarryH

Thanks for the help. I have applied Brad's suggestion, and will have to wait for more cruising to see if it worked.

08-Jul-2011 Rose Point Staff Member brad

The technique of disabling the BallPoint Mouse suggested by Nobeltec and The Capn usually works only for a short time and then the problem returns... When using an adapter with the FTDI chip, using the driver's option to prevent "enumerations" will prevent the problem for as long as the adapter is used with the same computer.

08-Jul-2011 steverow

What always worked for me years ago when this used to happen a lot, was to start the PC and let it settle completely, then start up each NMEA stream one by one, GPS first. For some reason it aways used to do it with my old garmin 235 plotter sounder, but not with anything else. But of course that was on my very old Sony Vaio which had PS/2 mouse input and I guess win2K always looked for that first. There have been various attempts at fixes over the years by Microsoft and others, but I dont think it's ever "really" gone away, just pushed under the carpet.


14-Jul-2011 waterman480

Brad - you are an ex Microsoftie - why is this relic still around causing hate and discontent for the last 10 years? When was the last time anyone even owned a serial mouse? (On the other hand - I thought everyone knew how to cure it by now.)

14-Jul-2011 Cullins

Back around the early release of Windows 95, or perhaps earlier, when my company was a Microsoft Partner, we brought this to Microsoft's attention. That was back in days when Microsoft techs used to drive over to our office to get a demo of bugs first-hand. Despite acknowledging this issue, Microsoft has never fixed it even in the latest update to Windows7. But, you know what, the sun has continued to come up every day, so life is good. Cheers, Mike. (btw, guess where I work now? Ha, ha!!)

14-Jul-2011 steverow

I also seem to remember it happening on 3.1 with TTL and RS232 inputs into another serial port usually the 25 pin when a serial mouse was connected to the 9 pin. It used to screw up the kids data logging projects in the sciences big time. Bring back the 68000!!


14-Jul-2011 Rose Point Staff Member brad

I am an ex Microsoftie... I cannot explain why they do or don't do things now (not that I really could when I worked there).

However I can guess that it has to do with backward compatibility with legacy devices. COM ports and anything connected to them are considered legacy devices and have been for many years now.

It is possible for manufacturers of USB Serial Adapters and USB GPS Receivers (which have USB Serial Adapters built-in) to bypass the check for data at startup (which is what starts the crazy mouse problem) but most of them don't bother. (Of course we do, however, in our GPS Sensors.)

Luckily FTDI did at least build the ability to permanently disable crazy mouse into their device driver. USB Serial Adapters based on FTDI chips are currently our favorites...

Crazy in BC
15-Jul-2011 RainShadow

I am in northern BC for the summer. PLEASE don't tell me that the Rose Point GPS does not cause the crazy mouse problem! I have stopped it, at first with the unplug it system and now with the disable the ball point device system (this seems to work)

Running windows 7 64 bit.

Crazy Mouse is a known problem in MS Windows
29-Feb-2012 BillHere

Hi, this is known (to Microsoft) problem in Windows. When Windows starts up, if it sees certain types of activity on a Serial Port, it will "decide" that serial port has a Microsoft Serial Mouse (or similar device) attached to it, and it responds to your device as though it was a mouse.

For Windows 2000 and XP, they have issued a patch to correct for this problem. It is called "ComDisable" - this does NOT disable your COM port, it disables a specific type of enumeration. This patch does NOT work for Vista or Windows 7. I have formally requested Microsoft to fix this problem and they have refused to do so.

This problem frequently occurs with Serial GPS units and with Weigh Scales.

This is the Comdisable URL

There are various threads on Microsoft and other web-sites.

Search the Microsoft Site for Windows 7 + USB GPS becomes Serial Mouse = Bad News

Good luck - complain to Microsoft - if they get enough complaints they will act (I hope).

Crazy Mouse Trap
17-Apr-2012 PilotHouse

Hey Guys,

Here is a Crazy Mouse trap that works well for us. It works well for both onboard Comports and external USB Comports. You may have to do a little work though.

Obtain the correct version of "DevCon.exe" from the MS TechNet website. original version for XP was v5.x I think. For Win7 Pro x64 it is 7.1.0.

Google: "How To Obtain the Current Version of Device Console Utility (DevCon_exe). This article also explains how to extract DevCon.exe from the .iso image. There is also a link in here to download the image itself.

Place a copy of DevCon.exe in the path, somewhere like \Windows\System32.

Create a bat file (Mouse_Trap.cmd) with at least this line:

devcon /r disable @serenum*

Place "Mouse_Trap.cmd" in your startup folder? (May or may not be ok for your situation).

You might also be able to assign a hot-key combination to a shortcut that you can run if crazy mouse pops up because of a new port.

You may have to restart a couple of times for it to get each port, but once it does, you should be good to go.

This should get all comports.

Good Luck Pilothouse