If you are looking at flat display, ou will have chroma information running below 7.5 and above 100% that is normal try not to allow it to get too far below or above. If the chroma starts to run too much below base line it can cause video breakup, because the signal can look at that and think it is sync and try to lock to it. &.5 black is a guide, and should be watched when looking at IRE settings.
Uh by the way reading your equipment setup, need any help?
Charlie