What is the CODEC you used when converting?
Use the free http://www.headbands.com/gspot/ to find out
Some other reading...
I have NOT used those products, I only forward due to other mentions
Edit Vob http://premierepro.wikia.com/wiki/FAQ:How_do_I_import_VOB_files_/_edit_a_DVD%3F
$70 http://www.nchsoftware.com/prism/index.html Converter
$40 http://www.deskshare.com/dmc.aspx Digital Media Converter
$00 http://www.squared5.com/ MPEG Streamclip Converter
$00 http://www.erightsoft.com/SUPER.html Multi-Converter
$00 http://www.virtualdub.org/ Mpeg to AVI Converter
Has the dvd been proper authored.
Or has it been made in a dvd recorder, the later can give problems.
I just recently took some vob files from a dvd and put into cs3....tried a few ways to do it...as it's quirky...have done in past as well as the other day....
I use "streamclip"
export from streamclip as a mov file....( I tried avi first and got video but no sound...then I tried extract sound but it was out of sync ( different sampling rate probably). exporting as mov file worked...muxed and in sync. I have quicktime pro and you might need that to have the codecs to do this.
its kind of a "trial and error" thing...depending on how the vob was made.
forgot to add...
if streamclip asks you if you want to fix timecode breaks..say yes...
start with vob 1 ....and if it asks if you want to include other files say yes ...it will attempt to bridge the vob files into one file...as the vob has a limited byte size...