Screen freezing and powers off

My tablet constantly freezes up. Half the time it powers off by it's self then starts back up. The other half of the time I usually have it powers it off. I've wiped everything off it (hard reset) and I've also hit the small reset button on tablet. It says it's currently up to date with P909. I've did everything I could think of and I still have issues. Tablet is also in good condition. Hardly used due to this problem!