DVD playback problems

I am not quite sure how to explain this problem but here goes.
I took some of my dvd’s to my daughter, but when she puts them in her dvd player, there is hardly any color. Exactly the same thing happens when she tries viewing them in her son’s Play Station .
However, the really odd thing is, that apart from the fact that they played perfectly on my own dvd player, they USED to play perfectly on hers as well.
They recently got a new TV when their old plasma developed a major fault, and I wondered if the TV was the problem…but if that’s the answer, then how come they wont play on thier sons Play Station 2 which is in a different room - attached to a different TV set.
(Most DVD tapes play perfectly for her…it’s just a few that this happens with…and it’s not the disks I am using, because a movie i put on one for my grandson works perfectly)
I hope somebody can help, and sorry if i havent explained it properly.
Regards to all