generally a black line denotes faulty display panel,look for sparkles.try advancing contrast, brightness,colour settings to max see if line flashes or disappears.i had 1 line on my plasma for about a year which has progressed into 8,i have managed to reduce this to 3 by totally dissmantelling it and removing all the glue on the edge connecters and resoldering them,in a way you are lucky only to have 1,when anyone visits and asks what the lines are i just tell them its an internet tv thats on line , good look
daz, July 2009