erratic mouse problem on a Compaq

I have a problem with a Compaq Armada 7400 notebook that the mouse suddenly goes erratic and uncontrolled, various windows pop up without warning, but nothing to do with the internet as I was not online at the time. I ran Winstone 99 which finishedwithout errors. This has happened 3 times in one day. It has 300 Mhz, 64MB, 6GB, CDROM, external floppy. Can anyone help?