Occasionally, my cursor slowly moves in a straight line right across the screen. Also, my computer has rebooted on its own a few times recently, after a software crash. I originally thought I might have a Trojan virus and someone is playing around but my virus definitions are updated weekly and I even did an online virus scan that found nothing. I also use Zone Alarm and don't giver permission to suspicious programs to access the internet. When the mouse is moving, I don't see any light flashing in the systray for the internet connection or for Zone Alarm, so I assume that means that there is no internet activity going on. I'm running Win XP Pro. Any help you can offer is greatly appreciated. And yes, I did check for ants around the mouse ball.