hi i take it your monitor is a crt type  check and see if you have whats called a degauss button in the monitor and press it if there is not one what you can try is with the monitor switched on using the speaker ( place it close to the screen and in a slow circular motion slowly moving back from it till you cant see the patterns changeing anymore on the screen it might work if not you will have to get someone that has whats called a degaussing coil to do it
                 vlf125
                
 July 2007