I have a Samsung DVD recorder that does the same thing, albeit not very badly. I think it's the DVD recorder that's at fault- when it's switched on, it is processing the analogue signal that it's being fed, and whilst you'd hope that it would output an exact copy of what was being input, it's not perfect, and that's most notice on any large areas of white or yellow.

Short of making all the connections digital, I'm afraid I don't have a solution for this.