I ran into this issue in an older home that had way out of date wiring. They had cut off the ground pin on cords to use today's gear. Somewhere along the way a bad thing happened and they lost their HDTV like this.
This is not an area you want to be a beginner in. But I think most folk would be better off if they checked all their plugs with one of these. Link follows.
Just last week I was replacing a wall switch and was not pleased to find the prior electrician omitted the green wire connection. They didn't connect it plus put some tape over it. "That's not good."
the samsung technician that investigated the problem with our beautiful new $3000 hd tv, informed us that its motherboard was fried by our direct tv box. Although samsumg warranty will cover damaged component, he strongly recommended getting a new dvr box from direct tv. guess what they said