First of all, I'm new to this... never done it before, but I think I done it all right and I simply don't understand what is wrong.

I downloaded the movie Monsters Inc. It's fine... it has a little intro (not just the movie) which kinda gets in the way of syncronizing the subtitles.
The movie is in 23.967 FPS.

I downloaded the subtitles (from divxsubtitles.net) in MicroDVD (.sub)format (25 FPS).

Right away I realized it was totally out of sync because of the intro thing... so I found the correct "start point" and used SubAdjust to resync it. It worked fine.

The source .sub is in 25FPS, does the target one need to be in 23 or 25 too? Or even better, does the subtitles file NEED to be at the same framerate as the movie?

I tried that too, converted the .sub to 23.967 FPS.

The problem IS: until 15 or 18mins of movie the subs are in perfect sync, then at some point (not sure exactly where) it looses it by 1sec, then 2secs... then by 40mins it's like 4secs out of sync.

I tried using both TextSub and VirtuablDub's subtitles plugin. Same result.

What am I doing wrong? Maybe the original .sub file? I tried a different one (.SSA) found in another site.. same problem.