My Toshiba Plasma tv cinnema edition 42 inch. After about 4 hours of watching the picture messes

Question

After about 4 hours of watching the picture messes up its red and green yellow exc you can see image but its messed up transparent like. This only happens after its on for a while normally works fine for 2.5 hours if i let it cool for 3 hours it will work fine again and then go get messed up into about 4 hours of viewing maybe a loose solder joint anyone have this issue