Variable plasma picture quality

Most likely it's that old problem- inconsistent digital cable signal.

Do you have a DVD player hooked up? If so, is that picture as good as you'd expect? If so, that rules out any panel issues.

You can call your cable company- or get DirecTV or Dish :)

Thanks Danlib. I do have a DVD player but haven't watched any movies on it except cartoons for the kids, so I don't have a good reference for comparison. I'll try a couple movies and see if anything looks amiss.

I'd love to try satellite, but too many trees around.

Digital TV is compressed. Some of it is good some is bad. Chances are you are not looking at an uncompressed HD quality picture like you would get from a BD player (so you see artifacts from compression or worse you are actually watching an upconverted 240 signal - half the resolution of DVD or what used to be normal TV in the olden days).

Also what are the pixels on your Panasonic - is it indeed true HD (1980 x 1020 pixels or 1080p) - most of the very best TV transmission are no better than 720 at the moment anyway.

Chances are is is the quality of what is being sent to you that is variable and which is causing variations in image quality. With 1080p you can really tell the quality of each program - some BD's in 1080 P are lousy and some - like Planet Earth BD are exceptional.