-Troubleshooting the mouse comes down to replacement in most cases. The mouse can and does go bad. This is usually do to the insides of the mouse getting gunked up. Most of your problems with this are do to bad care of the mouse. Its always a good idea to just clean the insides with a Q-tip and some alcohol.
-Also take note that if your mouse is functioning incorrectly it may be the cable itself, connector, keypads, or just worn parts that are causing you trouble. Sometimes just cleaning it can renew the life in the mouse. Before jumping to conclusions on your mouse, go ahead and clean it first.
-Shut system down and unplug mouse from port.
-While unplugging look and make sure no pins are broke or missing on your connections.
-Turn mouse over and twist ball plate. You may need to push down on plate while turning.
-Remove ball and clean with Alcohol
-With Q-tip with alcohol on it, clean roller bars. Clean all the interior of mouse and allow to dry
-Place ball back in and put ball plate back together securely
-The track ball is the same as above. Simply twist ring on base of track ball and remove ball itself.
-Try keeping work space clean. Clean your mouse pad itself and replace it as needed. Mouse pads have a tendency of growing fur after a while and getting nylon fragments into the mouse. Make a habit of cleaning the mouse regularly and your mouse will make it for years.
-Hopefully this helps your mouse operation. If not replacing the mouse is recommended. They are cheap these days so don't worry.
-Some other common problems that will cause aggravation is the keyboard. Keys tend to stick or not function at all. What can you do to fix this? You can clean the keyboard and pray. Or for 10.00 you can replace it..
-The keyboard seems to be one of those parts that goes bad real quick when you spill soda on it. The best thing to do is keep all liquids off the desktop. Keyboards in general work well and take a good beating. Sometimes keys and key pad sensors will go bad. This is just normal wear and tear on the keyboard.
-Now if you spilt a liquid on the keyboard you may want to remove one key at a time and clean underneath them. This will take a while. If this doesn't sound like a good idea then we can clean it air. By using some compressed air and blow under keys. This may not do much good if the liquid is soda or something with sugar in it. Yes, it will dry but the keyboard will be have a tendency to stick. Now if a key is sticking you can pry key off with some finesse and clean with alcohol.
-Another common problem is keyboard isn't sending a signal to the computer. Check connection first. If this seems to be okay then your keyboard may be faulty itself.
-If your keyboard is a constant problem simply replace it and forget about it. They cost 10-20 for a typical Windows keyboard. Make sure and get one with a Ps/2 connector when possible.