I'll read through those posts in a moment but was interested in how you're doing your movies. You're encoding video with TMPGenc correct? And how are you created the VBR AC3 5.1 file? I'll take a look at nandub.
lol and Microsoft's response is so very Microsoft, if they'd freaking tell us how they encode it then it would be a bit more helpful.
I've taken Batman Begins and split it into two parts, the first at 70 minutes is 2,131,925,694 bytes is NOT openDML and plays back without any glitches, the 2nd part is smaller and also plays back without issue, however, if they are combined together into an openDML AVI then voila you have glitching.
So it's pretty obvious that there is some sort of issue related to openDML, AC3 5.1 sound and the Xbox 360.
I'll post back after reading the threads you mentioned.
Iskondi