Don't know if this may help anyone but the other day I popped a game into my non-modded xbox and it came up with the error video you get when you put an xbox disc in your PC. I took it out and put back in and was fine.
Before hand I was playing on Live! and I took the disc out. Put this other one in and it came up with the error video. I know the xbox use 99% PC stuff and a stripped down version of windows 2000 so maybe somehow it got into the windows of the xbox. I dunno. Maybe one for the Xbox Linux crew to investigate.
Just a possibility, this is probably nothing but if it is nothing, just discard anything I said.
Good Luck!