1. I had just received a level-up when a dragon began circling. After taking a few potshots at it, I decided it might be wise to complete the level-up before facing it, so I did. When I finished, the dragon had disappeared.

2. I was fighting a draugr dungeon boss, and after his first hit my sword and shield disappeared. The shield I later found in my inventory, but there was no sign of the sword either in the dungeon or in inventory.