[Hellstrom]

I've noticed this and have always assumed it was some creature that set it off. It's always been a sonic trap for me as far as I recall.

I have also noticed DarkRanger's unnamed, invisible creature that goes away... but I never connected the two things. I always assume that creature was in a temporary position and got moved via script to it's final position. But maybe not.

Traps are springing all over. With all of my characters I have noticed I just walk into a dungeon or crypt and traps go off.

I haven't noticed traps "springing all over". In all the instances I've run into there's a single trap explosion sound when I enter a dungeon. And it only happens sometimes, not every time.