311 Issue

[Winged Wheels]

I have both a 311 receiver (S-Video) and a 811 receiver (DVI) feeding to the same TV which were hooked up by DISH (311 is for SD as it looked slightly better than the SD out of the 811). I am not sure how to describe this other than to say that there now seems to be a noticeable pulse every 4 to 5 seconds in the signal. This is blatantly obvious when displaying the GUIDE all the words on the screen pulse/shift/jump/move for a second. It is more difficult to tell during an actual show, but I believe that there is a pulse shift in the color of regular material as well. Any clue as to what I am experiencing? By the way the "pulse/shift/jump/move for a second" does not occur on the GUIDE screen of the 811. Thanks.