Blue, red or green ghosting on a rear projection television is related to a miscalibration called convergence. Poor convergence is caused by the Earth's magnetic field and causes the three colour projectors (blue, red, and green) inside the rear projection TV to become unsynchronized. Symptoms include ghosting. It's distinct from reception-caused ghosting and is unique to projection TVs. Troubleshooting blue ghosting can be accomplished by performing some adjustments.
Scroll through the menu items on the television set-up. Look for a picture set-up menu item called "Convergence" or "Flash Focus." Select it and choose "Set" or "Reset" or similar. The automatic convergence setting will be performed and the blue ghosting should be corrected.
Look for the more elaborate, manual-style convergence settings if the automatic convergence failed to correct the blue ghosting. Select the "Start" function and a pattern of white crosses will appear on the screen. One will have a highlight box around it. There will be crosses with red or blue beyond their edges.
Move the highlight box around the screen and choose blue or red ghosted crosses with the joystick, or arrow buttons. The highlight box will turn red or blue. Move the joystick, or use the arrow buttons until the cross is white. Then move onto the next ghosted cross and manipulate it until it becomes white. Through this process, you are aiming the three projectors so that they are synchronised at various parts of the screen. When all the crosses are white, the blue ghosting will have been corrected.