Very strange ... I had a problem like that with the image on an LCD HD TV, which was traced to a failed component in the TV. But the signal going to the SB should not be affected in such circumstances. Do you get the same washed-out image when viewing your SB on another computer? Or when accessing the SB via a web browser instead of the Slingplayer application? I am wondering if the problem could be a failing component in your computer, or possibly a problem with one of the 3 video component cables connecting your cable box to the SB input side, so that the video signal coming in to the SB is corrupted.
It seems that you are having some issues with your Slingbox PRO-HD since the video signal is "washed out".
As a first step, I recommend you to verify if all the video cables (red, green and blue for Component or the yellow one for Composite) are properly connected. If they are, I also recommend you to use a different set of cables in order to narrow down the possible root cause for this issue.
You can also check this link in order to get further details that might help you to fix this issue.