thuddy

I'm trying to finish the Alduin's Wall quest. I've gotten to the Sky Haven Temple, and Esbern follows me in and starts the dialog about the wall. He moves to the corner, but then just get's stuck. He doesn't move the dialog along even after I've chosen the two dialog possibilities. Delphine hasn't moved from the entrance to Karthspire. Does she have to be there for the dialog to continue? Any help would be great. Thanks.