It's difficult to pinpoint a diagnosis. I'm not sure what would cause horizontal colored images to appear. The best advice I can give here is to have your unit inspected by a technician.
Samsung DLP Model HLR5067WX, about 4 years old. Cable
Had a problem with the color wheel about 4 months ago. I changed it and put in a new lamp, all was good again.
Now I am having a different problem. The digital stations are broken up to the point you can not watch them. They have horizontal red/pink and white rectangles flashing on the screen. The HD channels are much better and we can watch them. If you concentrate on the background of the HD channels you can see small flashing colored squares, but not bad.
If I hook it to Composite Video (Video Out to Video in) it works like the digital channels.
If I hook it to Component (Pr, Pb, Y) it works like the HD.
Video games (Wii) works like the digital channels.
I know this is not a very good description but any help would be great. Thanks in advance.