Why does the mouse always move to the bottom left?

In the course of doing stuff on the computer, the mouse always moves, by itself, to the bottom left of the screen - I'd say several times in the course of an hour. I thought this might be an issue with the driver, so I re-installed the driver, but the problem continued. Then thinking that the mouse is faulty, I replaced my Microsoft Wheel Mouse with a Dell mouse. The problem still continues.

How can I fix this problem?

Are you on a laptop? The trackpad or thumb mouse may be faulty. See if you can disable it in the Control Panel or its configuration application.

If you use a mousepad, it could be the culprit. Mousepads with pictures can make your mouse pointer move alone or make your mouse pointer "jump" non-smoothly when you move it. The best mousepads for me are with solid colors.

I also have this problem on my Windows XP PC with a Pentium 4 processor; I assume it is because of the speaker's magnetic effect on the mouse.
I have tried lot of fixes, but the problem continues. I suggest to keep the mouse away from your speakers if you have them