Well, if the brightness or contrast is up too high, you'll get nasty flickering in the whites. But it could be your footage as well. If you turn on range check in FCP, are there any range warnings?
Calibration is a bit of an art. If you know what you're doing (I mean, like a television engineer) you can do it pretty much by eye, but there are also machines to do it more accurately. Set up is usually done with Colour bars, which is why we traditionally add colour bars to program heads.