Blue halo is a problem with reflections in the optical system of the set. It will occur under the right circumstances no matter where the signal originates.
If your set shows the problem with the "check signal cable" message or with my halotest.jpg
file, then it can happen during normal viewing, even if you don't notice it.
I first became aware of the problem, with my set, when I was watching a letterboxed widescreen movie (approx 2.4:1). Blue and purple blotches were showing up in the black bar at the bottom and stayed there if I paused the movie when they appeared. They didn't appear when I viewed the same scene while playing the movie on my computer using its monitor.
Look at the "heroes" image from an old post
by me, if you want to see an example of the problem in normal video.