Samsung PN50B850 - changes input and stops responding

I'm new here, I searched archives and found one message with a similar problem but no solution.

My PN50B850 works fine for anywhere from 15 minutes to an hour while watching TV or an HDMI movie...then without warning it switches to PC input (no PC input is connected). When it does this the IR light on the front panel blinks rapidly and the only remote function that works is volume up/down and channel up/down. You can't change input, punch in a tv channel, etc with the remote. Also, the touch panel on the front of the tv also does not work at this point. The only way to reset this is to pull the plug for the TV power and then all is well for another 15 minutes to 1 hour.

Troubleshooting so far
1) wiped down touch panel buttons...still happened
2) removed TV remote batteries before the TV went nuts...still happened
3) removed all remotes from the room (dvd, receiver, etc)...still happened
4) disconnected absolutely all other inputs from the tv....still happened

Does anyone have a true service manual for this TV to let me know which brain of the tv controls the input selection? Or does anyone know what the true problem is here. If not, i'm force to find a Samsung repair man and I absolutely hate not being able to fix something myself.

Thanks
Chip

Update --- now it changes channels and will increase volume on its own. The only way to stop and reset this is to unplug the tv. Doesn't anyone on here have any ideas? ? ?

Ok, i've given up on you guys. I still don't have a solution but here is something that did not work. I was advised to unplug the touch button control from inside the TV. I pulled the back off, unplugged the touch button, put it back together and absolutely nothing worked. Wouldn't even turn on. So I restored it to its original state, and have given up on this TV.

Hey Mauprix

The solution was too simple. I installed a new IR receiver board and the problem was solved. I can't believe I fought this for so long and didn't find a solution. It's been a few months now and the problem is definitely gone. I hope this helps, post back if you try this and it works for you too.

Thanks,
Chip221