I downloaded a set of vobs that I'm trying to turn into an avi, using DVDx v2. There are two IFO files (video_ts and vts_01_0) with the vobs and I've no idea why (when I've made my own, there's only one).

If I try to encode the avi using the video_ts.ifo, it says it's unable to parse the IFO. If I try with vts_01_0.ifo, I get a "cannot find the DeCSS key" error.

Is there something wrong with DVDx, or with the files, or should I be using a different program altogether?