You might be
1. using a trial version of the propreitary codec, being used by the DV.
2. OR the Tmpgenc may be a trial version. Eg. I used to have the same problem with DVDx2.0 Trial in the old days when it used to stop encoding after a particular frame range was reached.
3.Or check the frame in the preview window of Tmpgenc. Check either for the 17280 frame no(NTSC) or 14400 Frame No.(PAL). If you scan around these 2 frame ranges, you should be able to see what the problem is.