My Samsung 50" DLP has a fuzzy blue line running horizontally across the bottom left of the screen. It is about 1/2" wide by 14" long. As well, the HD channel black out for about 2 seconds 3 times a minute. After the 2 seconds black out, the picture restore itself without any intervention.
A Samsung service technician had a look at it and suggest I replace the color wheel and the controller board. Both a very costly and my warranty expired.
I am thinking you have an engine/board problem as well. A service contract would have helped. Samsung offers an extended warranty directly I believe... might want to check that one out.