I’m getting the same problem though from a single source (rip from broadcast capture HDD->DVD). Here’s what I’ve found:
It is only on the second segment of my two-part DVD.
It happens on the second segment EVEN if it is merely referenced to a later chapter within the first timeline.
It ONLY appears once the DVD is burned (only on a DVD or DVD image, not while previewing in Encore).
It does not appear in PPro or Encore in preview.
I had hoped it would have quit occurring when I got a PC upgrade, but to no avail.