I have an LG 42" Plasma with a green and red line on the left side of screen??? HELP?

I bought an LG 42" Plasma TV back in 2005.It has just recently (1 mth )developed a set of lines on the left side of the screen.The line was Green at first.Then it became a green or red line and it comes and goes when it pleases.Some say it could be an interference but it has never done it before and I have"nt added anything?I am thinking of switching from Cable to Dish anyway.Should I do that first to make sure it isnt the crappy cable svce that has been terrible all along?Please let me know if any of you have any experience in this area or know of anyone that does?