Scenarist VOBU error

[PhillipWyllie]

I've had this error a few times now, with the only solution to delete the offending chapter. The error is also shows itself when the track is multiplexed from within the track-editor and Scenarist just sits there and has to be re-started(forcefully), delete the offending chapter and everything is fine. Here's the specs for the video:

video
21:52:14 PAL
audio
21:52:13 2:0 ac3
chapters
00:01:19:00
00:04:03:17
00:05:41:16
00:07:05:13
00:10:32:23
00:14:31:00
00:17:11:18
00:20:59:17

error
Error The number(563727.0) of frame in a VOBU is more than 25.00 (around 00:21:51;20).
Error dvd_mux : DoMux Multiplexing Error
Error Terminated Multiplexing.
Error Number of frames in a VOBU is out of DVD spec. Please check MPEG video file or move CELL boundary.
Error Multiplex is failed.

Error MuxFromDB:MuxVTS failed
Error Multiplex failed
Error DVD Video files could not be created

Moving the chapter either 1 I-frame before or after didn't fix the problem(although in other projects where this happened, it did). Also re-importing the video asset again, after deleting the vif file proved fruitless. Re-encoding the video(with same chapter points) gave the same error.
My question is, what are the DVD-specs on VOB units, what are VOB units, and why is this error occuring? So I can try to plan ahead in future projects.
Thanks in advance.

[bigotti5]

A VOBU is the smallest unit of playback. A VOBU usually contains one GOP and is from 0.4 to 1 second long, unless the last VOBU of a cell which can be up to 1.2 seconds long.
Max GOP length for PAL is 15 frames (0.6 second).
Seems Scenarist is not able to mux your streams meeting that requirements

[Corion]

As far as I know, Scenarist needs a sequence header at the beginning of every GOP. God knows why. Does your encoder give you the option of "insert sequence header on every GOP". If so make sure it's ticked or whatever.

[FrozenDog]

Re-encoding the video(with same chapter points) gave the same error.

Wouldn't this mean that the encoder is inserting an I-frame at the same location recreating the same length GOP that Scenarist is choking on?
Error The number(563727.0) of frame in a VOBU is more than 25.00 (around 00:21:51;20).