I didn't notice this mentioned, so I thought I'd throw it in since bugs appear to be getting fixed. There are two bugs related to the "monster going in a berserk rage" mechanic.

The first is that the monster will apparently choose a random target to attack, which can sometimes be itself. When this happens, the monster will promptly commit suicide, producing a rather amusing message "The -foo- goes into a blind rage. The -foo- attacks the -foo-! The -foo- is killed! The -foo- suddenly looks more power."

Ordinarily, this is mostly just an amusement, although it can be annoying if it triggers on quest monsters (Kranach, for example), since this will mean that the PC will be denied the reward for completing the quest.

The second bug results if this effect happens to a pet. This results in a very, very, annoying situation, where the game will repeatedly save and quit, right away. If you're lucky, you can maybe get 1 step, and then it will save and quit again. This will persist until the pet dies, the PC leaves the level, or the player quits in frustration.