EAccessViolation
$77BA2237
Entered second bonus level (from lv4, I think). Got the chainsaw, was AFK for a sec, and when back I noticed the error. Did nothing after getting the 'saw except scrolling the BLOOD FOR THE BLOOD GOD message to read it. The game managed to save, anyway, and on my second try nothing weird happened. Perhaps the fact that I didn't need to get the chainsaw (it saved with it already in my inventary) had something to do. Or not.
EDIT: Again an access violation at $77BA2237, this time while navigating E1M9. Not sure, but I think it was between turns, not on an actual action. It seems it saved fine.
EDIT: I just noticed that I didn't say what version I'm playing. It's 0.9.10, FWIW