There does seem rather a lot of evidence that points to a problem in 1.1.2

The vexing thing is that it seems to occur only for some people, even though they are using the same versions of DVDDecrypter and the same DVD (my Harry Potter is R2 PAL, by the way).
During testing of 1.1.2, before its general release, I did notice that a full disc copy of Disney's 'Lilo & Stitch' gave a menu problem with one of the extras - a travelogue of the Hawaiian Islands. In this case the menu simply didn't appear. Unfortunately, Erwin wasn't able to source this DVD and so wasn't able to reproduce the problem. In any case, I think it might also have been present in 1.1.1 I'll have to dig it out and see.

I think this will be hard to pin down. If I were Erwin, I'd start by asking people who experienced the problems to email me their IFO files (both sets - ripped originals and DVD2One's), since it seems probable that this is where the answer will be found. Indeed, if anyone wants to send them to me, together with their exact settings used when they transcoded, I'll have a look too.

-Pete