Go to the settings menu, to the Source Options tab. (I think that's what it's called) Doubleclick "Source Range" to open the Source Range menu, then move the selector to the far right. (End of the video stream) Hit "mark as end position", then hit the down arrow on the "end frame" field once. (i.e. Mark one frame from the end as the last frame to convert) After that it should list the file's runtime properly.
Also, I suggest you use the CQ encoding option, set to 100% with a max bitrate of (9848kbps - Audio bitrate). (Example: You have a 384kbps AC3 audio stream, so your max video bitrate would be 9848 - 384 = 9464kbps)
Keep in mind that to be DVD standard your video + audio bitrate should not exceed 9848kbps. I doubt most DVD players would have trouble playing it if it were, but who knows.
If this is confusing -- and a lot of times it is -- feel free to PM me and I'll try to clear it up.