HDMI signal getting lost

I keep losing HDMI signal to my television.

I have tried seperate HDMI cables and I have tried both HDMI ports on my TV and I keep getting the same result.

The TV flashes between snow, green, snow, red, snow, green and repeats. Eventually it will either go to all snow or the tv will show "no signal".

I can switch over to Antenna and signal is fine (doesn't look good, but works)

The only way to correct it is to reboot the set top/dvr.

this is my 2nd DVR/Set Top box that AT&T has sent me.

Any suggestions?