I too am having this same problem. Everything was working fine and then a couple of days ago this problem started up. It does it on my Hopper and the 2 Joeys. My TV does not have PIP so I know the problem isn't there and the PIP on my Hopper is turned off. I've tried a couple of different media servers on my PC and the picture is still the same, a very small picture in the upper right corner. I have always had Dish for my TV but if this problem continues without any kind of fix or answer, I'll switch over to DirecTV...at least they have good customer support and really work to try and fix any problems.
I have rebooted my hopper and joey multiple times. I have a older hopper with sling its one of the hoppers with 4 tuners ( 3 for tv 1 for the sling ) It seems everyone having this issue has the firmware that was released on last thursday ( april 6th ) This was not an issue before said firmware. Happens on all my movies. My hopper is connected by wired internet connection. They joey is connected only by rg6. Issue happens on both devices.