That's odd. Something weird about region 2 release? Not sure how to interpret your problem.
First of all, have you tried with DVDDecrypter set to detect mastering errors? It's in settings under CSS. Try it with and without.
If all else fails, I got a sure-fire method for you. I once used it to get rid of extras before there was anything like VobBlanker, TitlesetBlanker, et. al. It preserves working menu for scene selection, no extras at all. One thing: menu does not autoplay, you have to hit menu button on your remote. Or you could use IfoEdit to make menu autoplay instead of main movie, I never cared to, and don't save menus any more.
Well, here it is:
Open up the DVD in DVDDecrypter in File Mode. In the window on the right, highlight and extract ONLY these files: VTS_xx.IFO and associated VOBs. So you'd want something like this: VTS_01_0.IFO and VTS_01_0.VOB, VTS_01_1.VOB, VTS_01_2.VOB, etc., all the VOBs in that titleset. Put 'em all in a folder somewhere.
Open the folder in DVDFab 0.17.1 (free, available at www.mrbass.org), click "Create Video Manager" (Video_TS.IFO).
That's it, you got an autoplay main movie and a non-autoplay menu. Or reauthor just the movie in DVDShrink. Not a very long movie if I remember, shouldn't have to compress much at all.
Hmm, doesn't AVG have two versions on the disc, the extended one with a couple minutes extra at the beginning? If you want that one, you might have to replace the first VOB and insert the alternate, renaming it in sequence, of course.