Help with my glitchy 360...

[El Xando]

As many of you know, my 360 got 3 red lights. I sent it to Microsoft and have had it repaired for about 2 months, but recently another problem began.
My 360 is connected via HDMI, and everyone now and then the screen flashes red then the video and audio both cut out and my TV displays "HDMI 1, Unknown". Usually after a couple of seconds, the video and audio come back, and the TV displays "HDMI 1, 720p" as it usually does. However, occasionally it just doesn't come back until my 360 is turned on.
Also, I am getting a new monitor soon which I am going to plug my 360 into instead of my TV. Me and my dad bought a DVD/VCR hanging bracket so we could hang it off my desk, which we put it in earlier today, since the new monitor will arrive next week. I plugged my 360 back into my TV and put it back on it's shelf, with the bracket on. This made the 360 be leaning forward a bit, which I thought wasn't a problem. After 1 or 2 games of Halo, the video cut out again, and didn't come back. I tried tilting the 360 back to level with my feet, and it came back. I then let it down again, and the video and audio disappeared again. It's not even a big change in angle.
What on EARTH is wrong with my 360?

 

[Abe Froeman]

Bad HDMI cord maybe? Or just level it off on that shelf since it appears to correct the problem.

 

[El Xando]

It was doing it before when it was just on the level shelf, I just noticed it was more frequent when tilted forward which I found strange. I don't think it's the HDMI cable as that wouldn't explain the strange red flash and why it works most of the time. Also, I can't find out if other people have had similar problems because when I search Google for a red flash all I get is RROD and when I search HDMI video audio problems or whatever it just tells me about the update made to fix HDMI audio...

EDIT: Trying with component now, no problems so far, and it is still tilted forward right now. If there are just not problems it will be very odd since the HDMI cable had no problems before the RROD... If there are no problems, it's either a dodgy cable, or the HDMI port on my 360 is screwed up for some reason. And I am getting a new HDMI 1.3 cable with the new monitor so that will establish whether it's the cable or not. Going to test it more.