I'm sorry to hear you're having these issues with your television.
That's definitely not normal operation for the television, and I don't have any reason it's something you did to the television. I also would have thought it was the cable box or some sort of handshake issue, but I haven't heard of the transparent green screen issue before.
I would definitely set up a service call at 800-SAMSUNG and have a tech come out and take a look.
Keep me posted. I'd be interested in hearing what they diagnose.
I have a Series 5/500 LN40A500T1F 40" Samsung LCD TV. Last night, after being off for an entire day while at work, I came home and turned on the TV. No more than a minute after being on, a loud squelching noise and green screen appeared over the existing picture (as in it was semi transparent) I unplugged everything immediately. Plugged everything back in, turned it on, and same thing. Thinking it was the cable box, which connects to the TV via HDMI, I went and exchanged the cable box. Everything was fine the rest of the evening.
Tonight I was watching a DVD on my Samsung BluRay player, after having the TV for a few hours watching normal cable without problems. About an hour into the DVD, same thing. Again, turned everything off and problem was gone upon reboot. The movie finished, about a half hour later and began to watch regular cable again. No more than a half hour later, same problem - loud squelch, green screen. TV is unresponsive to remote and only "fix" (if you'd even call it that) is to manually shut everything off.
We purchased an extended warranty when we bought the TV 3-4 months ago, so I'm not worried there. I'm wondering though if this is something on my end, such as the power strip everything is plugged into, or a defective set of HDMI cables....
Any help would be appreciated.