Cannot scrub DVD on some computer players

I have a DVD that when played on some computer DVD players the user cannot scrub forward on the "timeline" in the DVD player software. They can skip, FF/RW, etc. but cannot just pick a spot to click on and jump to that. I have all user operations enabled for all the tracks. This works fine when using a DVD burned from a set-top recorder, but not with DVDSP discs. Also, on my Mac with the built in DVD Player software it works, but the same disc played on a windows machine does not work on a couple players. Any thoughts what would cause that or how to fix it?