Television and Home Theater

HI, WHEN I SWITCH ON MY T.V. IT WILL STAY ON FOR 3 MINUTES AND THEN SHUT ITSELF OFF INTO STAND-BY MODE, AND WONT COME BACK ON TILL I DISCONNECT THE POWER TO THE T.V. AND THEN THE SAME THING HAPPENS AGAIN,

THANKS IN ADVANCE.

MODEL NUMBER IS; 36ZD26P  L.C.D.

Well I have a Panasonic PT-47x54 Rear Preojection TV.. Its just about 2.5 years old.  THe other day the picture went from good to looking convexed.. The top, bottom and sides are off the screen now..the center of the picture is OK but the sides are messed up.   I called the service company and they said its a pincushion circuit...$20.00 for the part, $150 travel labour and $50 an hour, figures in and around $300 to fix it.

Recently my samsung plasma 4243 tv screen  started going black w/sound.  When I turn it off for a couple of minutes it would come back on fine andgo for an hour or more.  Now it stays on for 20 mins and goes black, it needs to stay off longer to come back on with a picture.  Also now when it goes balck it has vertical color stripes flash right before it shuts off.  Of course it is 2 months out of warranty so samsung says it is not thier problem and will not even work with me on the problem.  There is only one samsung approved repair service near me which opens