I was deep in the CoC when I got the "You are attached to ChAoS corrupting your foes" corruption. I didn't pay it much attention, since I could still kill chaos monsters easily. Did the Mana Temple, Earth Temple and went for the Air Temple. I get Yulgash critically injured and then he transforms into a writhing mass of primal chaos. One more hit and it's dead. By this time I was surrounded by summoned nasties, so I retreated back to the corridor and took care of them one at a time. When I go back to pick the corpse and orb up, I can't see them. No problem, I think, something must have picked them up. I empty the temple of all creatures and I still can't find them. "Oh, shi-"
Yeah, I'm pretty sure that Yulgash didn't drop the Air Orb. To top it off when I returned to the stairway where I had dropped all my items, they were also gone. Zapped a wand of monster detection and killed everything (including a ghost which I thought had stolen my stuff) but no luck. Weird game.