Obviously you're doing it wrong, i use nero Vision for it, it re-encodes and assembles movies into DVD format (all files and folders) and I can safely burn it on DVDs.
The trouble is the subtitles, I think. It kept only burning the first 1:55 of the film to disc, which coincidentally also happens to be the point where the first dialogue appears. But when I tried to mux the subs in manually - using the exact same program DVD FLick (which is the DVD authoring software I've been using for years) uses - they work perfectly. It just breaks somewhere else instead.
At one point I got it working, only to find that the size was a couple of hundred megabytes larger than it should have been, and it wouldn't fit on the disc. So I re-encoded the audio at a smaller bitrate, then when I went to make the DVD again, it no longer worked. At all.
Now I've reached the point of putting a fresh install of DVD Flick (which is what I usually use) on a virtual machine, and trying again there from scratch. Hopefully it'll finally work.