Did read my PM to you on Tuesdat where I said:
"This morning I ran across more material of people with CRT-based televisions who have experienced the exact same kind of dotted lines. In most cases these lines come from interference of some sort, which might even include faulty cabling to your TV. From my own experience I know that audiovisual cables do wear out after time.
I would start by having someone move the cabling around while you're watching to set, as sometimes this shows that the cabling is sensitive."
As I've stated previously on the forum, I reached the conclusion that the dotted lines were not your TV, but had to do with signal coming into your inputs.