A "checkerboard" pattern usually indicates bad RAM or the contacts between the sticks of RAM and their sockets are corroded. Try removing the RAM and cleaning the contacts on the sticks with a pencil eraser and a light application of denatured alcohol. Take a small pencil-thin wire brush and clean any debris, corrosion, etc. loose from the sockets as well. Then reinstall the RAM; you can even rotate the sticks, much like rotating tires on a vehicle. Turn it back on and see if the symptoms happen again. If they do, you may have capacitors that need replacement or further cleaning to do. Oh, and don't forget to check the PRAM battery (3.67 Volts or greater).

73s de Phreakout. :rambo: