I'm having this same problem...and not my first Gateway either. I find it happens "often enough" when I am pausing live tv. I can't trust it to do what it is designed to do. I frequently have to pause the program to take the dog out or whatever.
I go to restart and get the black window that tells me it has lost connection. The only way to get it back is to change channels. Of course I just lost the segment of the show that was paused. Tonight I missed the second goal of the hockey game. Before I have missed the end of a movie.
Very frustrating when you can't rely on your equipment.