I have a couple of ripped DVD's on my computer which import as a bunch of separate VOB's rather than a single movie in MC. I did some investigation and found that they were both missing the VIDEO_TS.IFO file which is necessary according to the DVD spec and it's what Media Center keys off of for importing a DVD movie. I can think of 4 reasons this file is missing:
1. I accidentally deleted it at some point in the past (dumb).
2. Media Center overwrote it somehow (bad).
3. The ripper was unable to copy it because of a scratched disc or some weird copy protection scheme.
4. The file is not required by the DVD spec. and was never provided on the disc (I may be wrong about the spec. but I doubt it
Please post in this thread if you've had similar DVD import problems. If it's at all common, we could make some improvements to handle this better. For example, in my case, there was a VIDEO_TS.BUP file available which is an exact copy of the IFO and Media Center could automatically use that if the IFO file is missing.