After lots of re-installs /downloads I think I finally figured out what is making most of these beta crashes/problems.

Every time I install vanilla sins impulse auto downloads the entrenchment beta, which is great saves me a few button presses. But instead of downloading the original beta it just downloads the latest patch. And since I’ve done a clean install of vanilla sins it has none of the 'old' entrenchment files, and thus nothing to update.
And obviously this makes the game unstable and causes it to crash.

Hopefully this helps a bit in getting these strange problems sorted.

Greets