By the looks of it you have removed the target glow aura to your "target frame" settings but you have not removed the glow aura from your "player frame" setting. I do not have Pitbull infront of me atm but I know that it is one of the options for when you are targeting some one and you can make it brighter or dim it down to nothing.
You can disable PitBull4 [Highlight] from the character screen to get rid of it completely.
If you don't want to do that...it's probably somewhere in the layout settings. Sorry I can't be more accurate.