When you say AdobeViewer crashes and it won't open again, are you talking about the same book or a different one?
I had a similar experience with the June 14 15.2; a book I converted via calibre from HTML crashed the AdobeViewer. When I tried to re-open it, nothing happened. I opened a *different* book (no reboot) and all was well.
Oddly enough, at the time, I created two books in calibre.
Both started in MS Word; one I saved as HTML the other as a LIT.
The LIT one, when converted to ePub worked fine to the end; the HTML one loaded abnormally fast and crashed when trying to get past the cover.
(The cover isn't a 3:4 aspect ratio image so that's something else I need to look into.)
The point about the Themes is interesting; I live in FIVE and except for the one file, 15.2 is stable. I'll try going to DEFAULT and see if it makes a difference.
Nope. No change.
Of course, the problem file works flawlessly in FBReader, giving the lie to my observation that Calibre unduly favors Adobe's interpretation of ePubs.