Q1: Do you colour correct or colour grade to a LCD or CRT screen/monitor?
Q2: Does your finished DVD look good on your primary monitoring device: LCD or CR?
Firstly, check to see if this "second" screen is setup correctly and not over saturated.
Secondly, play a previously made DVD on this "second" screen. Does it too look over saturated.
Thirdly, have you used EITHER a Studio RGB to Computer RGB OR Computer RGB to Studio RGB Fx any where in your workflow.
Fourthly, what MPEG template are you using to create the video DVD files?
I'm guessing but I think you have created a DVD that looks "good" saturation on your monitors, but this HAS produced over-sat on your second monitor, whatever that may be.
In terms of col-sat I have 2 ways of preparing DVDs: 1xLCD, correctly set to match closely my CRT. This way I am covered for both eventualities.