It really depends on how the footage has been ripped. Retail DVDs are generally authored with far more complex processes than you'll be doing at home, or even in small business/studio/corporate situations. The biggest issue of ripping commercials DVDs (store-bought DVDs) is the extra data found in the VOBs. Many commercial releases come with subtitles, extra audio streams, and layer break markers.
Clearly, you've run into an issue where you're hitting something non-video/non-audio in the stream. I would suggest you're running into a chapter mark or layer break, leftover from a basic rip/extraction.
You'll have to further purify the VOB to base MPEG video + Audio, using the process found in this guide --
http://www.digitalFAQ.com/guides/video/edit-dvd.htm -- for
help ripping retail DVDs.
There are several methods, but this one has proven itself foolproof for years.
The only times these methods fail is when the authoring work is further complicated by advanced next-generation anti-copy methods (beyond basic CSS encryption). For example, when a video is jumbled on the disc, and nav data is coded into obfuscated IFO directives. PgcEdit and DVD Shrink have proven themselves useful for this, but I've seen discs where nothing can fix it. At least nothing that has any sort of automation -- advanced authoring knowledge required (above even what I know, and I'm no beginner!)
Sometimes Restream is require for further purification of a video M2V. More on that at
http://www.digitalfaq.com/guides/vid...ield-order.htm. Also note that you won't be reversing the interlacing, but instead selecting the other options: Remove, Remove, Reset, Zero.
OBLIGATORY NOTE: Anybody reading this should remember that ripping DVDs in and of itself is not "illegal activity" -- that's just silly. It's really not uncommon for post-processing work to be based off a DVD source, under certain professional workflows. Clients (studios!) obviously give permission for the content to be extracted, and for it to be re-purposed for other needs. Sometimes the expense of going back to pre-DVD sources is not a justifiable expense, where output quality will be essentially identical with either workflow. There are also educational considerations. Many people are unaware of the goings-on in the professional video community, knowing little more than what they see on blogs written by (obvious) non-pros.