Rippling Effect - Spybot Disk Cleanup Defragmenter

Janet has a "Time" Notebook which has developed an odd effect when scrolling ( pages, or lines). Instead of the page or line moving downwards smoothly, it ripples.this happens whether she uses the built-in mouse or one plugged into a port.It's a PS2, if that is of any use.She has a new optical mouse and XP found the software for it but the rippling happens with the new mouse as well.Any ideas would be most gratefully received.The Notebook isn't here with me.We've run Spybot, Disk Cleanup, Defragmenter, and a scan when the computer is switched on. She uses Zone Alarm and AVG Antivirus.I downloaded XTeq Setup and set the number of lines to scroll (3) but the same thing happens.