We have just set live the last update to the beta.
In it we have addressed the major crashes that players have provided .dmp files for, fixes, and several optmizations. We will continue to work on the game up until the point of release (and after of course).
If you crash report it here. However, the majority of crashes are the result of being out of memory. So the first thing you should try is to lower your settings (especially textures and world detail).