WS1.0 cannot cope with MPEGs that have no audio in them. Not silent... NO audio
I created a photo slideshow in another application that used a 15min 23sec piece of music, but had 15 min, 40sec of pictures (end title and fade-to-black on playout). When trying to burn a DVD, WS1.0 returned a "Failed To Convert Video File"... after managing 98% of the damn thing (around 20 minutes processing time).
Painstaking and time-consuming investigation eventually showed that those final 17 seconds of silence without any audio track was the culprit... add a suitable "soundtrack" of silence (using a file I called "40 seconds of silence.mp3"!) and the problem is cured.
AC3 handling
To reiterate posts mentioned elsewhere, AC3 is a Dolby process, and "Dobly" (apparently) require a fee paid for each use of their encoder. Therefore the TRIAL versions of ULead software do not implement AC3 handling, as you've not paid anything yet! So if your DVDs are coming out silent, check that your source material is not encoded with an AC3 audio track.
In both cases, a better error catching system ( "Failed to convert BECAUSE..." or "AC3 not supported in Trialware" ) would have saved me (and probably other users) long and frustrating hours of investigation... I am still trialling DVD Workshop to see if I can put up with its idiosyncracies...
