How to explain this...

I have been using TMPGEnc DVD Author for a couple of weeks. Everything has gone well for the most part. But I've got a bit of a stumper. Every once in a while, when I use TMPGEnc DVD Author to edit and create a DVD compliant program, TMPGEnc DVD Author creates an "extra large" volume.

The files I am working on are recorded from a Hauppauge PVR250 card using SageTV. All the programs have been captured in the same manner. The shows are either 1.5hours or 2 hours. I get two 1.5 hour shows (with commercials edited out) or one 2 hour show per DVD. But, again, I have had a few captures where the result of TMPGEnc DVD Author created volume is far larger than it should be. Not sure what is going on.

Anyone else encounter this problem or aware of a solution? I am still on the trial version of this program. It was my intention to buy it, but I first want to get this figured out.
Thanks.