I am trying to get my Mitsubishi WD-65638 DLP working with my Mitsubishi 3DC-1000 starter kit to display 3D from my Comcast cable box (Motorola DCX3400) through my 1120. If I manually force the cable box to 1080i and connect it directly to the 3D adapter, it seems to work fine. But, when I connect through the receiver, the TV and the adapter seem to not get along and I cannot get a picture on the TV. The weird part is that I get occasional sound, mostly a black screen that says Invalid Format and every once in a while I get an all green screen that quickly goes back to black. I have even seen an occasional blue screen that gives some message about the HDMI signal being corrupt or something, but that goes away before I even get a chance to read it.
The initial reaction was that the receiver does not support HDMI 1.4a (even though it says it does) and that is the problem. The weird part is that I have my PS3 routed through the receiver and I can watch 3D movies from it with no problems at all. I have posted something on the Comcast 3D forum to see if anyone else has seen this, but I figured I would ask here in case someone knows if something in the 1120 might be causing issues. I tried using the exact same HDMI cables that I am using for the PS3, so I don't think the issue is a cable that does not support the bandwidth.
Any ideas? I have tried everything I can think of and have spoken with 3 different Comcast technical support CSRs who were no help at all. Could the 1120 maybe be doing something with the signal from the cable box that it wouldn't be doing with the signal from the PS3? Do I need to turn off HDMI control or something else?