I have the same thing happen about 4 to 5 times in the first month I installed the HD Pro. I am using component video cables from my AT&T uVerse box (motorola 1200). It worked fine for a few days then, suddenly --- no video feed. I could see the guide and popup channel banner when changing channels, but as soon as the channel banner went away nothing but dark screen and static.
I notice when I got back home and checked, the Slingbox was warm in my component cabinet. So I moved it to the top of the stack and put some spacers under the unit so it could get more air flow. I also flipped it upside down because the air vents are on the bottom of the box. Flipping the unit lets the hot air rise through the vent holes an exscape. The problem seems to have gotten dramatically less frequent, but it still does it about once every few months. Very annoying!
I think it is a temperature thing, but not sure.
SlingMedia -- Please HELP (comments) ??!