This thread may contain spoilers, please go through it only if you've finished the chapter "The Tomb of Sammun-mak":
I'm on the burial chamber now. I told the Grandpa Mole that I am from Sttutgart and he spelled me. I didn't understand what the spell did, so I tried to ask him. When asking for spells, I was given the options: "We are NOT from Sttutgart", to reverse the spell i suposse, two more about spells I think, and the typical "We want to talk about anything else".
I clicked on one of the other spell options (Benny's Course, i didn't know what was that), and I ended up in another choose dialogbox with no options. I can't go back to the menu (menu not available in this mode), I can't load, I can't save, I can't exit. I can't right click so the conversation ends.
I'm playing the Steam version.
Edit: I can reproduce this. All the times. Just let the Grandpa mole curse you and then ask him about the Benny's curse.