I also have this - video drops but audio still ok. When video drops, seems to last for several seconds to a minute. I found that if I use back 6 secs, it picks up after the break, but of course, the audio is lost as well with this method.
My dvr is R15-500 and firmware appears up to date at x136B.
After fighting with this for what feels like 4 months or so, I am ready to call DirecTV for a replacement. I have already done the gross reformat operation at least twice so the hdd is real suspect.
I called DirecTV again today on this issue and they said they were aware of the video drops but also several other issues:
1) video stops while audio continues. Timed at 6 to 40 seconds.
2) remote fails to control the receiver even while the blue light on set indicates a valid signal - happens for moments to a few minutes.
3) while #2 occurs, the navigation buttons on the set are also inop.
4) audio stops completely while video works and channel changes are ok. Again moments to a few minutes.
The response from DirecTV is that they will not replace these receivers since the problems are known (I have the equipment protection plan); they are not offering any idea as to a schedule for a fix; they are supposing that these are software problems; they will not discuss a receiver upgrade unless associated with a national/regional upgrade plan.
Perhaps if more of us call and complain, this might lead to a fix. As it is, I have been with them for over 10 years and they don't seem to consider a potential loss of my account as of particular interest.
I have grown to like the channel lineups offered, and the service used to be great.