I spoke to soon.
S9 is back to it's old tricks, just will not render a 56 minute DVD.
I tried re installing again but this time no luck.
In the end, I used the free software that came with my new PC, namely Windows Movie Maker and then burned it using Nero. Still looks pretty good and without all the hassle. S9 is just a pain and I'm not using it again. Maby I'll try the new S10 if it comes as free trial.