Question : Problem: 3mm black spot on my plasma screen when certain films play (why)

I have a 42 inch Hitachi plasma screen. I notice that on some movies, i get a black patch, very small but you
can see it with the naked eye.

Think is, put on sky 1 or news or most other things and you don't get it but some films, you get it.

What is the reason for this and what is it. I have a 5 year gte with john lewis, so is it something that i should be worried about and take it back for.

Answer : Problem: 3mm black spot on my plasma screen when certain films play (why)

it's very odd that it is just on one channel and you're right if it was dead pixels then they would stay dead. Are you able to connect a computer to your screen? If you do you can use something like this to make sure there are no pixel issues
http://www.softpedia.com/get/System/Benchmarks/Dead-Pixel-Tester.shtml

but given that it's only on one channel it's highly unlikely.