I entered into the grotto and when i try to talk to him, it looks like the conversation is bugged...
I found nothing in web...ideas?

Did you try re-loading your Auto-Save? (it should be about 5 minutes back)
Did you try leaving the cell and returning?
Did you try reloading a Save before you got to the grotto?

Conversation bugs usually fix themselves by doing one of these things.

First not worked/Third Tried
Second Worked
Thanks