You haven't specified the model, so we don't know what type or model of rear projection television you own (e.g., LCD, CRT). The most likely cause of this problem, if you have a CRT rear-projection television, is that the blue gun is badly out of alignment. Rear-projection CRT televisions often go out of alignment when they are moved and can drift out of alignment over time. Other types of rear-projection televisions are less prone to alignment problems, but may also become misaligned. Your television should have an automatic alignment feature, accessible from the remote. Check the user’s manual for instructions on how to automatically realign your television. If this fixes the worst of the alignment problem, but you remain dissatisfied with the results, you may want to adjust the alignment manually. You will need to invest in a video calibration DVD, which can also help you calibrate the screen colour and brightness. I use a calibration disk called "Digital Video Essentials", made by Joe Kane Productions. Such products can help improve the image quality on most televisions, but you need to take the time to go through process properly (one to two hours). The user's manual should include instructions on manual alignment. If not, read on. If you are not handy - or ambitious - you may want to hire a professional to do the job for you. I would recommend using a technician who has been certified by the Imaging Science Foundation (ISF). Any such person will have the proper equipment and skills to do a professional job. They also have access to more detailed technical information on calibrating your television than is available to most consumers. The ISF website - http://www.imagingscience.com/ - provides a list of businesses than can provide such services. However, before you pay a professional to align your television, make sure that the problem is with the alignment. If not, there may be a more serious problem with your television that can only be rectified by having it serviced.