This happened to my Samsung Plasma in dec'05. The panel got a 1" yellow line in the middle from top to bottom.
My warranty was over. Luckily, i got the Havey Norman ext warranty for another 2yr.
Called up HN, they sent Samsung tech to access the situation, Tech told me that the panel has chemical leakage, need to change the entire panel, which is abt $2.7-$3k.
HN customer serviced called & gave me 2 options:
1. proceed with repair, HN will pay.
2. get a new Plasma which costs $3k, anything extra, i need to top-up.
So i got a new LG plasma at $3k. Paid for another 3yr ext warranty. LG agent warranty 2yr + HN ext warranty 3yr = Total 5yr!
Have read up at other forums that many have had their LCD/plasma tv with panel problem, 1yr warranty over, no choice, got to get new tv. There goes their $3-5k investments.
Seems wiser to get an extended warranty then ...