I assume you are running the DVD audio and video through the AV 7000, and you have already indicated that you have made a component connection to the monitor (the plural "terminals" implies audio as well, which suggests you have the add-on speakers). You don't indicate the Xbox connection method, so I have to assume that's through the AV 7000 as well.
One thing I found on the monitor is the S-Video input takes precedence over component video, so only the former will work if both are used (BTW, there's a noticeable improvement in picture quality using S-Video, particularly with the DVD player). Also, mixing the two types on the receiver may be to blame.
I recently purchased this display and hooked it up to my home theatre system (Harmon Kardon AV 7000). I purchased the HDMI terminal card for the display, and connected that directly to my Comcast cable box (Input 1) and that seems to work fine (HDTV and straight digital signal). I hooked up the BNC terminals on the display (Input 3) to the RCA terminals on the AV 7000 via custom cables with a BNC connection on one end and a RCA connection on the other end. The DVD player (Harmon Kardon DVD-22) works fine (audio and video), but I can only get audio when I try to use my X-Box, and nothing with the VCR (which I may have hooked up to the cable box incorrectly). The display indicates "no signal" when I attempt to use either of these devices.
I suspect the problem may be in setting up the display so that it recognizes the signal source from the VCR and X-Box, but from my reading of the instructions so far, I haven't been able to grasp exactly how to do that (I consider myself to be enthusiastic, but not technically gifted).
Can anybody offer any wisdom that might steer me in the right direction (i.e., save me from having to read the manual a dozen times to figure it out)?
Thanks for reading this, and any direction you might be able to provide.