I have had this problem for about the last two years, off and on.  There is some sort of program working in the background of my computer and even THOUGH I have reformatted my hard drive, it still surfaces from time to time.
This is my problem:  Sometimes my scrolling bars go up and down without me doing anything.  If my MOUSE was last over a particular window, which has a scroll bar, it will go up and down on its own.  When I roll my cursor, using my mouse, over another window which has a scroll bar, it does the same thing and the previous window will stop moving.  It is only when I have my cursor over an active window with a scroll bar, that this occurs.  When I remove my mouse from the computer (USB) and start using my keypad/pointer, I do not a problem.   One weird thing is that I eventually get irate over this activity and start seeking assistance, LIKE right now.  Once I do that it stops; or so it seems.  This will happen again in the future, at a time that is not good, which is always.
I am careful about not opening spam mail and other emails that could be dangerous, but something has a hold on my computer and it sucks.
So, it is only when I use the mouse, only in an active window with a scroll bar, and it comes and goes for about two or three days and then leaves me alone.
Did you try another mouse, PS/2, possibly?No I did not try another mouse.  I had considered doing so, but my computer is back to normal again...I will do that next time.  I posted this because I though this was something that others may have experienced before.  I did remove TEMPORARY files from my computer and rebooted to see if that would make a change.  It actually did make a slight change and maybe that is why it is back to normal.  It is really an anomaly to me.  My mouse is a Microsoft, Wireless Intellimouse, Explorer 2.0.Good job
Thanks for posting back.This is funny. From time to time I was experiancing something simular. For no apparent reason my mouse would center on the MONITOR. After a while this became an annoying occurance. I changed the batteries, changed the receiver position and it got worse. After a week or two I gave up on the problem and decided I have to live with it. A few days later I was relaxing watching TV. My pc is about 5 feet away from the TV. I changed the channel using the remote control and noticed the mouse cursor centered. Tested it about 15 times. Bingo. Problem found. Problem solved.