Mine are also on the left side of the screen and dissapear after 20 minutes or so. Now there are actually lines on the right side, they start as black and then fade to red and the red doesn't go away. Have you had any luck finding a fix?
I have owned the LCD tv for about two years and never had any issues. We recently moved and when the TV was reconnected, there are 2 or 3 really thin black lines on the left side of the screen. They run from the very top to bottom of the screen. They are only about a milimeter wide and they actually disappear after the TV has been on for 15-20 mins. I've tried using different HDMI cables, reconnecting the cable box, using different HDMI outputs, and tried the Blue Ray player. The lines appear everytime. I called Samsung's help line and they don't really seem to know what it is. Can anyone help?