running around mouse.

HELP!!!
I can't find a solution nowhere. Here's the problem. The arrow of my
mouse on the screen just starts running around whenever it wants.
When I touch the mouse it immediately stops but a few moments later it
starts running around again. I suppose it's some kind of a program
that is running but I can't find it and stop it. I don't like it
because it's difficult to work with the mouse that way.
Can anybody help me or give me some advice to find a solution?????
Thanks.