I understand that you are having some issues with the Slingbox AV since you cannot get the video signal.
Most of the times, this issue is related to the connections on the home network. First, I encourage you to check if the Slingbox shows the same behavior watching it through www.slingbox.com. I also recommend you to verify that the cables in use are connected in a proper way. The following link will provide you with the steps to follow.
Make sure to follow the included instructions and let us know how it works for you.
The new all-home DVR system with Cox uses the Cisco Explorer cable boxes.
SOMETHING IN THE FIRMWARE PREVENTS BOTH THE HDMI OUT AND THE COMPONENT OUT TO BE USED SIMULTANEOUSLY!
Actually if the HDMI out from the cable box is plugged in then the component outs do not work.
The claim is potential future FCC regulations.
If you unplug the HDMI from the TV or the Slingbox and just use the component out from the box to the Slingbox then you will get both the hi-def picture and the sound instead of just the sound.
My previous DVR from Cox allowed both the HDMI out AND the component out from the box to both work simultaneously.
I now have to get yet anohter cable box (slave) to just use for Slingbox! Somewhat ridiculous, I know. Trying that tomorrow but should be successful as a work-around.