Are all your speakers shielded? Not sure if that has anything to do with it.
You also may want to try the internal color calibration. On my rear projection there is a "color magic" option that will ballance out all the colors in case they may have become misaligned. Not sure if your set has this.
Also may want to throw a call into the manufacturers customer service center. If they are a good company then they may have tech support to walk you though an easy fix or point you in the right direction.
Good luck.
