After one year of non-use I started up my iMac G4 20" 1.25Ghz last week, when I noticed two discoloured spots at the bottom of the LCD screen. They are in the shape of a wave, each about 3cm wide and 2cm high. Both are located 10cm from the edge of the screen (symmetrical). (see attached image) You can only see these spots with a light background. The mac has always been stored in a dry room. So I am not sure what may be the cause of this defect. Is there an easy fix for this problem? Or do I need to replace the panel?