From DCS forums =
Just a tip for anyone experiencing crashes with the Rift.
I can only speculate about the bug causing the crashes but I do know
if there is only one aircraft slot in a mission (and it is the designated as player) then you try to spawn straight into the cockpit BUT this seems to cause a crash.
if you add a second aircraft (as a client) to the mission then when you run the mission you initialise outside the cockpit with a world view and the slot menu and when choose to spawn into the aircraft you do not crash.
if you have CA and add a CA slot to the mission this is also true; when you run the mission you initialise outside the cockpit with a world view and the slot menu , and when you choose to spawn into the aircraft you do not crash.
Basically setup the mission to initialise with a world view instead of straight into the cockpit in VR. (You will have to edit MOST missions to temporarily fix them or wait for ED to fix the bug)
Will check tonight if I get time
Tony