1. Giskard already published HU 8.1. that should fix some bugs and problems with certain missions (e.g. in the Frankfurt System). I've found the new version here:
http://www.respawn.co.uk
Giskard's comment: "Hostile Universe V8.1 is now available to download. It contains lots of fixes, including several Treasure Hunt Clue fixes and the Snub fighter bug was fixed."
2. At his side Giskard posted on 3rd Sept.: "It has pretty much been confirmed that the Hostile Universe mission crashes are caused by Directx 9a or 9b and the 3D sound setting. Users have reported that turning these off has fixed the problem for them. It may effect others mod so if you experience any mission problems try reverting to directx9 and turn off the 3d sound options."
Hope this helps