Old DVD footage choppy on new DVD

Hey guys,

I have a sort of odd question for an odd job I'm finishing up. I have a SD montage here (FCS 6) that's been rebuilt from an older dvd with new footage, mostly from internet clips. However, the clients like a few of the older pieces, so footage from the old DVD is staying in the new project along with mostly new (controllable) footage. I am in DV codec. Besides a bit of quality dropoff (it isn't that noticeable however, because some of the clips they wanted are of very bad quality), its been going smoothly.

However, I'm seeing some problems at the end with the older footage. Everything is fine until I go to the actual DVD, when that original DVD footage is incredibly choppy, almost like its dropping frames, looking almost like a bad SmoothCam render is trying too hard.

I've processed the footage using compressor (best quality 2-pass) straight from FCP, and also exported the file and used that in compressor. Also tried CBR as well. Into DVD studio, I built the DVD, and used both methods of burning (inside the program, and building to a folder and burning that). Everything is fine up until it processes through DVDSP, as even the preview there seems smooth. But all my processes and troubleshooting leads me to the point of the problem, and not the cause.

I realize its an odd question, but does anyone have any tips? Or have heard of this issue before? Thanks!

My edit rig:

Mac Pro (2007 version)
Leopard 10.5.8
Quad Core Intel Xeon, 10GB ram
ATI Radeon X1900 Graphics Card