i have the same problem. model ln40b500p3fxza. i got the tv from sear 2012 and in spring of 2013 the volume would go all the way up or would go all the way down. when it act up, i have to run to the tv to poweroff manual or pull the power cord. afterward, you plug back the power and the power button will not function. if i wait for about an hour or two the tv will work for again, until it act up again. i have own alot of TV, this IS THE ONLY BRAND I HAVE PROBLEM WITH. i am 40 year now, I HAVE NEVER REMEMBER GETTING PISS-OFF AT TV. I WILL ALWAYS STAY AWAY FROM SAMSUNG BRAND.

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