Solid vertical line on JVC 42WV74 (by 3 users)

We have had a recurring problem with out JVC for a while now. Sometimes, about 2/3 on the right side of the screen, a solid line appears from the very top of the set, and runs all the way to the bottom. It is about 2 inches in width. It changes colors, from a rainbow assortment, to then sometimes becoming solid black. Many days we can go hours without ever having the line appear. Then it will come up, and it can appear on whether a show is live, taped on tivo, or even when a DVD is played back. It will stay on the set, sometimes for only a couple of minutes, and sometimes for an hour or more. It always changes color unless it goes solid black.

There is no way to figure out what causes it to come on or leave. Not sure if it is the tuner box, the actual plasma, or one of the cable connections. My system is cable, with a DVR cable box, and a separate DVD player. That's it.

I can post a picture, or send one by email, of the actual line on the tv screen

THANKS in advance for any advice on this - by the way, we did have this 'fixed' under warranty by a local authorized repair shop, and for a while when returned, it seemed ok. Of course, it returned only after the warranty was over, and JVC won't help now.