Okay, firstly, if running Norton, you should setup an exclude for the Radarbox installation folder. If running Vista, also setup an exclusion for the Radarbox folders in the Virtual Store. That may improve the "freezing" problem.
Have you ticked the option in preferences to "Download Aircraft Photo". Without this ticked, RB won't retrieve details from Airnav's server. And when a new aircraft appears in the list, what do you see in the status bars at the bottom of the screen. Do you see "1 Processing Photo/Info Request(s)..."