You've got a bad MPEG. (A bad MPEG will often play back OK.) It's hard to tell if the DVD is bad or if you've got a "ripping" problem. You can also corrupt an MPEG simply by editing it. But, if all you did was take a 3-minute section out to make it into an individual file, I doubt that's the problem. (I had trouble when I joined a bunch of clips with transitions.)
Any one else had the same problem?

DVD importing problems seem to be becoming THE most common problem!
Video Studio is the best DVD ripping programs that Iknow of. But, it doesn't work on all DVDs.

It can extract the MPEG without re-coding it. Most rippers will decode and re-code the MPEG, which causes a loss of quality.
You can try another DVD ripper, or you can try
SUPER (FREE!!!). SUPER isn't really a "ripper". It's a conversion program and it can convert a VOB file to an MPEG-2.
The reason I say SUPER is not a ripper is because if you use it to "rip" a full-length video program, there will be glitches when you re-join the MPEGs made from the individual VOB files.