I have experienced multiple issues of the gateway rebooting / services crashing since the day it was installed. On the day it was installed, the installer had to return with a different unit. Approximately two weeks ago, I experienced the same issue again for about 30 min and it seamed to correct itself. Again about a week ago, it happened again and seemed to clear itself up. Now it has been doing this for about 2 hours.
I've had the same thing as well. The picture will freeze, then disappear. Then it comes back with a 5102 error, and after a few seconds says No Media Gateway Found. I have to wait a minute to two, before I can hit Live TV, and get the picture back. Mind you, this is happening on 2 receivers, and I have already had the gateway replaced once (for doing the same thing, and replacing it did not fix the problem) Sometimes the receiver will reboot as well (clock disappears, then comes back). This will happen if I'm watching live tv, the DVR, or even something through Home Connect.