I spent some time doing various things, then completed a bounty, made some char changes and extracted a few runes, total of maybe 1.5h playtime. At the end of this time I quit straight to desktop. The game did freeze for some time before shutting down. Almost the entire progress of the session seems to have been rolled back. Logging back in I got placed near where I had started, and xp, items, etc. were all as before, and the bounty unfinished.
Let me know if I can provide any files or other debug info