Well, probably I was not precise enough:
When I recode a DVD with Standard AVC in a one pass process, in most of the cases, the final file is ok.
In the case of 2 two-pass encodeing, the file is build up in a reasonable way during the 2nd pass, i.e. the file size grows and reaches the specified limit. But just before ending the encoding, the file size suddenly reduces to something below 40MB and I have a file with a black image and the audio from the movie only in the length of the movie.
Unfortunately, there is no log file, etc.
It is quite frustrating....