I have my tv hooked to my computer but there are two spots in on the right hand of the picture that are dis-colored, almost like there is a speaker(magnet) screwing up the picture. This does not happen to the tv whille watching cable, dvds, etc. Is this common? mabey the tv is getting old. Its not s-video just video composite. I thought it might be the speakers in the tv, but these should be shelided, any ideas?