I have a customer who claims there is a BLUE BOX all around the component video input? Does anyone know of an issue that would cause this? I say it is a resolution issue but was wondering if this could be a malfunction of projector ? HELP !

I work in a hotel and we are running a 1075 ceiling mounted through an extron crosspoint switcher. We have 5 RGB patch bays, 4 of which are generating noise and marching lines on the picture(not horrible but bad enough that people complain.) The one patch point that is working fine (the lines are still there but not as bad)is also the one that is closest to the control room, so I'm pretty sure this must be a cable length/interference problem not a ground issue. We have tried running a DA into the patch points but that gets us no-where. Anyone have an idea of what we can do... short of re-wiring the entire room with better shielded cable? Thanks!