I'm glad I found this forum, because there are many things to learn. Two years ago I purchased a seldom used G4 (dual processor). It is still very clean and works great. Since the past week the monitor has begun to flicker, more like ballooning outward, then shrinking to normal size. This includes all images, screen saver, and DVD movies. The flickering is only a split second and it occurs sporadically, sometimes every two minutes, sometimes once every 30 minutes. Also, I sometimes hear a click from inside the monitor when it flickers, as if a spark is jumping somewhere. Today I replaced the battery, cleaned the inside and added 1 gig memory in a vacant DIMM slot. But the flickering continues. Otherwise, everything works well as usual. Does anyone know what the problem could be?