With PGCDemux the problem you are running into is that you are trying to demux individual VOBs which IMO is not the way to go. Here's how I do it, and I suggestion you try it out.
When you open PGCDemux in the lower left is the box for Options. You want the following boxed checked:
1) Demux video stream
2) Demux all audio streams
I think "Create CellTimes.txt" and "Create Logfile" are checked by default (as far as I know that just collects info about the process).
In the middle of is a box labeled Mode. You want the circle to the left of "by PGC" selected with the black dot.
On top you have: Input IFO
So when you click the "Browse" button to the right of the Input IFO section, it will open up a box, then you want to find your folder where you ripped the DVD to. Once you find it (it should be a VIDEO_TS folder). Double click on it. I'm not sure how you ripped your DVD. If you ripped just the Main Movie or not. Assuming you only ripped the main movie there will be two IFO files. One is a "VIDEO_TS" IFO File and the other is "VTS_01_0" IFO File. You want the VTS_01_0 IFO file.
So once you've clicked and opened that, so the directory with that file shows up in the "Input IFO" section. Then you want to check the lower right. There should be a little white rectangle, with an arrow tab on the end of it. It should say something like "PGC #01--> 01:25:00:00" (you said your movie was around 85 minutes).
Now you want to browse for an output folder (that option is below the browse for "Input IFO"). Choose whatever folder you want, make a new one, something you can easily find etc.
Now go to the lower left and click the Process button and let PGCDemux work its magic.
When its finished you'll have the elementary video and audio streams you need to get started with your edit.
I hope this helps.