I have a Xbox that is about two years old, modded about a year ago, and has always worked perfectly. I've always had it connected via the composite cable, but recently, I tried connecting it to my TV via a component cable, instead of composite, and all I get is scrambled video or a blank screen. It continues to work fine via composite.
I've tried two different cables (both of them are multi-purpose PS2/XBOX/XBOX2 cables) and two different televisions. Both cables work great on my PS2 on both televisions. Either cable produces the scrambled video or blank screen with either cable or television when connected to the XBOX.
So I'm left with the conclusion that the problem lies in the XBOX itself. Any ideas?