Well, it was a bigger bug, than I thought - here is, what I wrote into the suggestion board:
In The Underdark: characters are stuck very often - two times it was the bulette tunneling under them and suddendly there was a pause symbol on every character and nothing happened. had to reload. Now I'm at the Myconid colony and talked to the dwarf lady that wants you to find her husband and it happened again. I can't do anything and have to reload. I can't save and reload on teh exact same spot, because the problem stays.
