Troubleshooting Mice

This section discusses troubleshooting of problems with mice or related to them. Like keyboards, mice are extremely simple devices that rarely fail and are relatively simple to troubleshoot. Since new mice can cost as little as ten dollars--even decent quality ones sometimes, believe it or not--they are in many ways items that you discard and replace when they stop working. Of course most problems with them are relatively straightforward to fix anyway. They are also easy to diagnose by swapping with another mouse.

The mouse is not working: it is not recognized by the system or the mouse drivers

The mouse is stuttering, sticking or moving in a jerky fashion

I have a PS/2-style mouse that I want to use on a serial port but it doesn't work when I use an adapter to convert it from the PS/2 6-pin mini-DIN connector to the 9-pin serial connector

The mouse is recognized by the system and there are no error messages, but I cannot move the mouse pointer in one or both directions (horizontal or vertical axes)

My mouse works under Windows 95, and in DOS boxes running under Windows 95, but not when I boot to DOS or "Restart the computer in MS-DOS mode"

Explanation: The mouse is not working at all. The system is not recognizing its existence and its drivers are not loading.

Diagnosis: This is of course sometimes caused by physical problems: the mouse cannot be seen because it is not connected. Using the wrong driver can cause problems on occasion. For serial mice, the problem is often trouble with the serial port itself.

Recommendation:

• Make sure that the mouse is connected physically to the correct port and that it is not loose.
• Check the mouse wire to make sure it has not been excessively twisted, bent or damaged in any way.
• If you have another mouse that you can try in place of this one, try swapping them and see if the problem goes away. Similarly, you might want to try your mouse on another PC and see if it works. (Remember that drivers are often specific to certain types of mice; you want to swap with another mouse of the same type, using the same interface, either serial or PS/2).
• If this is a new PC, check this section for troubleshooting possible general problems. In particular, there may be a loose or incorrectly connected internal cable to the COM port that you are using for the mouse.
• If you are using a PS/2 style mouse, make sure it is not connected to the (identically-sized) PS/2 keyboard connector. This of course will also make the keyboard not work properly.
• If you are using a serial mouse, you may have a problem with the serial port itself. Resource conflicts and other problems with the serial port are fairly common. Look here.
• If you just upgraded your motherboard and now your mouse is not visible, a likely cause is that you left the old cables that attached from the serial port connectors to the motherboard headers in place. These cables are not universal, and you might now have the wrong kind installed for your new motherboard.
• If you are using a PS/2-style mouse, remember that the mouse uses IRQ12. In some situations, this may cause a resource conflict with another device. Check here for more on resource conflicts.
• If you are trying to use a PS/2-style mouse on a serial port, or a serial mouse on a PS/2 port, you must use a so-called "combo" mouse. These are specially designed to be able to handle the different electrical signals that are used by the two different mice. Some mice will fit the adapters physically but will not function correctly because they cannot handle the different signaling levels required; this is described in much more detail here

Explanation: The mouse's motion is not smooth and fluid the way it used to be or the way it should be. When you move the mouse it tends to jump around or stutter, stops moving unless you shake it, or moves in a jerky fashion (the pointer seems to pause between redraws on the screen for example).

Diagnosis: There are four main causes of this sort of behavior. The first is a dirty mouse, which can cause spurious behavior in a number of ways. The second is a resource conflict with another device. The third is damage to the mouse cord caused by excessive bending of the cord, especially near where it attaches to the mouse. The fourth is a problem with the mouse driver, although this is much less likely.

Recommendation:

• Check the mouse to make sure that it is not physically sticking. Clean the mouse.
• Try using a mouse pad instead of your desk (or other surface) for rolling the mouse. In many cases the surface the mouse is on is actually the problem. Using a mouse pad allows the mouse to roll smoothly. (I have, however, seen desks that worked better without one.)
• There may be a resource conflict, especially with regard to an IRQ channel. This is especially true of serial mice, because of the fact that serial COM port pairs 1 and 3, and 2 and 4, share IRQ lines. See here for more on resource conflicts regarding serial ports.
• Check the mouse cord to see if it is frayed or becoming loose. If you see cracks in the plastic housing of the cord, this is a sign that this may be your problem. If you have a soldering iron and patience, you can fix the problem, but replacing the mouse is normally the action of choice here.
• There may be a bad driver associated with this mouse. It is unlikely that this is the case (since mice are such simple affairs) but is it possible.

Explanation: You have a mouse with a PS/2-style 6-pin mini-DIN connector for connecting to the PS/2 mouse port. You want to be able to use this mouse as a standard serial mouse so you connected it to an adapter that takes a 6-pin round mouse and converts it to a standard 9-pin DB9 serial connector. However, the mouse does not work when connected this way.

Diagnosis: The problem is that the PS/2-style mouse and the serial mouse are not just different in terms of the connectors they use, they are different electrically as well. The signaling levels are different, so just using an adapter will not always work. What complicates the matter so much is that there are some mice that are called "combo" mice, which will automatically use either the PS/2 or the serial signaling depending on what sort of system they are plugged into. This type of mouse, when used with an adapter of the sort mentioned above, will work in a serial port. However, not all PS/2-style mice are combo mice, and this is what causes all the confusion. To make matters worse, most mice do not have printed on them whether they are "combo" or not, and sometimes even the documentation is not very helpful. (Buying a mouse with a PS/2 port that comes with a PS/2-to-serial adapter is a good hint that it is combo, of course!)

Recommendation:

• Check the instructions that come with your mouse to find out if it is a combo mouse. If it is, then it should work with the adapter. Make sure the adapter is tightly fitted to the connector and that there are no bent pins or other physical issues. If the problem persists, troubleshoot the mouse more generally here.
• If you don't have a real combo mouse, or aren't sure if you do or not, then try borrowing one from another PC and see if it works instead. If it does, then your mouse probably isn't a combo and you will need to purchase another that is (or just purchase a straight serial mouse, really, if that is what you want). If the other mouse doesn't work, then you either borrowed another one that isn't a combo, or you need to troubleshoot your mouse setup more generally.

Explanation: The mouse is recognized by the system and the cursor (or pointer) comes up on the screen, but there are problems trying to move the pointer. Either the pointer does not move at all, or it only moves up-and-down or left-and-right.

Diagnosis: One cause of this problem, especially if the pointer only moves in one axis, is physical obstruction of the rollers within the mouse that are moved by the mouse ball to cause the mouse to work. Driver problems can also cause this behavior, as can electrical failure of the mouse itself (which is unusual).

Recommendation:

• Check the mouse ball to make sure it is rolling, especially if the mouse is new. I have seen mice that come pre-packaged with a piece of foam tucked around the mouse ball to prevent it from moving around during shipment. You can't tell that it is in there when you try to move the mouse; the mouse glides around but the ball doesn't budge. Boy did I feel stupid when I saw that after boggling for ten minutes as to why this brand new mouse wouldn't work.
• Open the mouse up and remove the mouse ball. Inspect the metal rollers (there should be two of them, perpendicular to one another). Make sure that they are moving freely. Try moving them by hand and see if the motion registers by moving the pointer. This may fix the problem. If the inside of the mouse is dirty, clean it.
• Try rebooting the system and see if the problem clears up. Occasionally glitches may cause the mouse not to work properly. If this happens a lot, I'd suspect a software installation or driver problem. You may want to update your mouse driver.

Explanation: You are running Windows 95 and the mouse works properly within the graphical interface (regular Windows 95). DOS programs have mouse support when run within Windows 95 (in a DOS box or window). However, when you restart the computer into DOS mode, or boot straight to DOS without starting Windows 95, your DOS applications have no mouse support.

Diagnosis: You do not have a DOS-based mouse driver loaded, and you need one. Windows 95 has native mouse drivers which function when the graphical user interface is running. The mouse driver loads when you start Windows 95 and supports both Windows applications and also DOS applications that run within Windows. However, when you "Restart the computer in MS-DOS mode", you are merely shutting down Windows 95 and staying in the DOS 7 environment that underlies it. This unloads the Windows 95 mouse driver, so you won't be able to access the mouse unless you load a DOS mouse driver when you shut down (or don't start) "true" Windows 95.

Recommendation:

• The best way to avoid this problem is to simply load a DOS mouse driver in your AUTOEXEC.BAT program. You should follow the instructions that come with your mouse to install the mouse driver. The mouse driver will be loaded when the PC boots up and will therefore always be available, whether the graphical interface of Windows 95 is active or not. The only real disadvantage of this solution is that a small amount of either conventional memory or the upper memory area is used up by the mouse driver. The native Windows 95 driver runs in extended memory (which is much more plentiful and not a scarce resource like conventional/upper memory).
• Place the line to invoke the DOS mouse driver into the DOSSTART.BAT file within your Windows directory (usually C:\WINDOWS). This batch file is executed automatically each time you exit to DOS from Windows ("Restart...") The advantage here is that no conventional memory is used for the driver unless it is actually needed. The disadvantage is that booting directly to DOS without ever entering Windows at all will cause the driver not to be loaded (you can still load it manually as described just below).
• You can simply run the mouse driver as needed; install the mouse driver and take a look to see what the install program sticks into the AUTOEXEC.BAT file. Then copy it to a separate file, maybe called DOSMOUSE.BAT, and place into a directory that is in your search path (set by the PATH statement in AUTOEXEC.BAT). Run the file whenever DOS mouse support is necessary.