PS2 DVD

The DVD player on my PS2 plays DVDs but when the dvd is playing the colour changes slightly. The picture is normal and then brighter what is this?
Also can you play American DVD's on your PS2, I am in the UK.
Cya
Rach

[Nex]

I'm french and I've a friend who had recently bought a psx2 and he havn't any problem for playing dvd
So, I think that you must try to read another dvd or perhaps your psx has a construction problem...