Original post by: lemerise ,
1- connect the PB to an external monitor to determine if the graphic processor (logic board) is faulty or not. If you have the same scrambled image on the external monitor then your logic board would have to be replaced to fix the issue. 2- The good news is that the problem seems to be intermittent so I would suspect a faulty LVDS cable (maybe you just need to reseat the connectors) or a faulty LCD panel. Check the LVDS connections, first to the logic board: step 12, LVDS connector is to the right side of the logic board [guide|258|stepid=913] then check the connection to the LCD panel (you'll have to open the display).