I apologize for not remembering exactly where I read it - I'm thinking it was on klar's website. This method allows you to get the book in Verhoffin's ruins with a low-level party. For my purposes, it can also let me get the book with a minimum of killing (I know I can do it with only 2 kills, not counting reanimations). The method exploits the Terrors' inability to open doors, allowing them to be avoided altogether by going into turn-based mode before opening the doors they are behind and moving only within the allowed TB radius. Both the key and the book can be reached in this way (sometimes also the chest behind the book, but I'm not good enough to reliably repeat getting it).I was not in TB mode when I cast Turn Undead. But I went into TB mode to get the key while Turn Undead was still active. I think that's what is messing it up.
I'm also curious now, since the only other time I had an infinite hourglass (in a different game) was in the Lich lab. I wonder if it is linked to the Turn Undead spell and is a bug that doesn't allow the party to take action while the spell is active (making the spell useless for people using TB mode).
I will probably just end up killing the two skeletons, since this is a minimum kill game as opposed to a no or low-kill game. Because Invisibility is not available in this game, some kills must be made for survivability (as the monsters will swarm you and render you unable to move otherwise). In this instance, I can't have the skeletons attacking me constantly because I need to be able to reliably close doors and they are likely to just open them or keep them open.