Screen shuts off, color dissolves to black (by 3 users)

I recently purchased a used Toshiba 50HP81 and it worked when I got it home. I was using it for about 45 minutes the first day and everything was fine and the picture quality was outstanding. The second day when i powered it on, red pixels came up in the bottom left of the screen and eventually the full picture came on after about 5 minutes of messing with the hd cables (which i realize had nothing to do with it). The picture since then has not stayed on for more than 15 minutes or so at a time before dissolving the pictures to black and having no visuals for about 3-5 minutes then repeating. The power/standby light does not blink indicating any errors. I'm thinking maybe there is something circuitry related and not screen related, but im new to plasmas and don't know too much. I would be able to replace resistors/amps inside if that was the case, but I'm not sure how to figure that out. Any help would be great, thanks.