After getting 3 recruits for Delphine, she tells you to talk to Esbern about going to some dragon nests and pwning some dragons. Problem is that when I go to Esbern, the icon for a quest-related interaction appears above his head but he doesn't say anything. He just stands there and keeps saying "yes" when you interact.

So this is totally breaking the quest line. Anyone else have/fix this problem?