Video card going out?
Also, if they are in a window, they will move with that window.
Could this be happening because of the video card going out?
The lines look just like this: http://farm4.static.flickr.com/3243/25990075431695b18555b.jpg
Message was edited by: Derek Collier
20'' iMac 2GHz Intel, Mac OS X (10.4.6), ATI Radeon X1600