Troubleshooting A Mouse


Anthony Olszewski

last modified:

Did the mouse ever work?
Standard Serial Mouse With A DB9 Connector

If the mouse was previously functional, were any devices recently installed? Any new cards, particularly modems, sound cards, and network interface cards might be using the same IRQ as your mouse. The mouse is generally set on COM 1 using interrupt 4. If it is set on COM 2, interrupt 3 will be used. (It is possible to use COM 3 and COM 4, but they have to share interrupts with COM 1 and COM 2. I suggest, for rock solid performance, to not use COM 3 or COM 4. The exception to this would be if you are using an "intelligent" IO card, that allows for additional interrupts.) The system hanging up in WINDOWS when you try to move the mouse is a screaming example of interrupt trouble. If you are experiencing an interrupt conflict, you will have to re-install the new device.

If no hardware changes have recently occurred, does the mouse work in DOS but not in WINDOWS, or vice versa? If the mouse works in WINDOWS but not in DOS, check your autoexec.bat file. Possibly, a line has been added that keeps the system from reaching and loading the mouse driver during the boot. Very often the DOS mouse driver is listed after the WIN statement in the autoexec.bat. This is a great memory saver, for you don't have the DOS mouse program just hanging around taking up memory while WINDOWS is running. When you exit WINDOWS, the DOS mouse driver will load. But if you try to run a DOS program IN (FROM) WINDOWS, the mouse will not function in the DOS program.

If the mouse will only move in one axis( i.e. you can go up and down OR back and forth, but not both) or if the mouse is dragging and moving in fits and starts, very possibly some dirt, lint, or just plain crud is bolluxing up the works. Turn the system off. Carefully remove the mouse from the port. Slowly take the mouse apart on a clear table. Expect it to just sort of fall apart at some point and be prepared for the housing and little screws to fall willy-nilly. When you get it apart, gently manipulate all moving parts. If any show resistance look to see what is the cause of the trouble. Very often a slender thread can wind about a little axle. The fabric can be carefully removed with the tip of a pin or a razor blade. Just putting the parts in motion often is the solution. A hand held vacuum is a great help. Don't get overly exuberant and suck the little bugger right up! Even if the mouse can't be disassembled, you can take out the ball and gingerly try a vacuum.

DON'T OIL ANYTHING! The ball can be cleaned with alcohol, if it appears crud encrusted or otherwise foul. DO try to keep the mouse pad and your desk in some semblance of hygienic order.

It's possible for the serial port itself to flake out or the connection of the card to be loose. This is rare. If the serial port is built into the motherboard and the mouse comes and goes, there might be a bad ground between the motherboard and case. You might have to remove the motherboard and use electricians tape to insulate the motherboard from the case. I've only seen this once as the root of mouse trouble. Again, if the serial port is built into the motherboard, you might have to run the SETUP program in order to enable the port.

If the mouse is just being installed, was there ever a mouse on the system? You just might have a lousy mouse. The $10 items don't go through a very rigorous quality control system. Make sure that the software is properly installed. Very often it's necessary to specifically indicate to the driver what COM port to use for the mouse. This is done with a software switch, most often MOUSE /2 or MOUSE /c2. It's not unusual for the mouse driver to install itself to the modem. This is why you will have to specify the COM port.

If the mouse is working, but erratically, have you tried a mouse pad? This $5 item might be all that you need.

Standard Mouse Connector For The 9 Pin Serial Port. If The System Only Has A 25 Pin Connector, Then You Will Need To Get a 9 To 25 Pin Converter.

Are you sure that your serial ports are working? Watch as your system is booting. Usually a hardware list appears showing, among other things, the serial ports. If the port is not active, the mouse will never work. If you don't get a list at boot, from the DOS prompt, (for version 6.X) type MSD. This utility will give you a good run down of the hardware. Again, if you don't see the COM ports listed, that will have to be addressed. The ports may have been disabled by jumper settings. With the system off, the serial card (very often also the IDE card) will have to be removed and the settings examined. If you are lucky you will have the manual for the card, listing the jumpers, or the explanation could be silk-screened right on the card. If this ain't the case, write down ALL the current jumper settings. You're not going to remember them. Now's the time for trial and error. Turn the system off. Remove the card. Change a jumper. Re-insert the card. Turn the system on. See what happens. If you don't get a new COM port showing up - turn the system off. Remove the card. Return the last jumper to its original setting. Try another one. Keep doing this until you try all the possibilities. You might just want to buy a new $10 serial port card and save yourself a lot of aggravation.

The ribbon cables and serial connectors are commonly defective. If the COM port shows up at the boot and in MSD., but the mouse driver can't find the port, this could be the problem. Electrical and magnetic interference can be the culprit. If you've got the case cover off, try putting it on. The mouse cable itself can act as an antenna. Try coiling it as much as possible. Flickering fluorescent lights and electric motors are real curses as far as this electrical pollution goes.

This Mouse Will Work In A Serial Port Or, With A Converter, In A PS2 Port
If the system uses a PS2 style mouse port, make sure that it is not disabled by a jumper. A fuse on the motherboard might have burnt out and need to be replaced. The gizmos that are supposed to convert a serial mouse into a PS2 mouse ONLY function with mice specifically labeled as convertible - SERIAL/PS2. THE ADAPTER WILL NOT WORK WITH MOST MICE! Trying out one of these instruments of torture with any mouse that you've got laying around is a great way to blow a fuse on the motherboard. This can be a real pain (soldering iron) to fix.

A Serial To PS2 Converter

If you've just installed WINDOWS 3.X and the mouse is not working, did you have the mouse plugged in during the installation? If not, WINDOWS saw no mouse. In any event, go into WINDOWS SETUP and see what's listed for the mouse. You almost always should have MICROSOFT OR PS2 listed for the mouse. If you see NO POINTING DEVICE, you naturally want to change it!

To be on the safe side, DON'T use the EXPRESS installation in WINDOWS 3.x! Perhaps half the time, it can't find the mouse! Use the CUSTOM installation. CUSTOM starts off with a table describing the hardware found in your system. If it has NO POINTING DEVICE listed (assuming that your mouse IS connected), correct it to show the appropriate mouse. In most cases this will be MICROSOFT OR PS2.

WINDOWS 95 really seems to do a great job of handling pointing devices. If you're having mouse problems in 95, first make sure that the mouse is not dead. If troubles persist, it may be the serial connector, cables, port, or the motherboard.

I recently came across a the wierdest mouse problem I've ever seen. The arrow was jumping all over the place -- it was literally bouncing off of the "walls" of the screen! The first thing I did was to run a virus check. This did detect and remove the anitiexe virus. I suspected that the crazy mouse was an effect of the virus. The next day I again tried the system. It worked fine. After a half hour it seemed a little jumpy. After an hour it was a nervous wreck again!

I again ran the virus check. This time the system came up clean.

Replacing the mouse solved the problem once and for all. It seems that the first mouse would work OK to start. Some component was probably overheating as time passed.