Are you saving within 50 km of anything (land, ships or planes) or while submerged? If so these are big SH III

's; they can cause crashes. Here's a good tip that I got from someone here: when you want to save, dive to a reasonable depth & perform a hydrophone check to listen for any nearby vessels. If there aren't any around you should be able to save your game after you've surfaced (as long as there are no planes around of course).
Hope this helps...
P.S. These are not GWX glitches. The 50km & saving while submerged bugs have always been in SH III & unfortunately the GWX team couldn't solve them.