My first thought was to go with "Kyle", but almost 500 entries of "Fulminorax" made me decide to change my answer to "Wilbur"... and yes, that's my final answer. ;)
I have the same issue. I tried talking to Rhix and got the same blank dialog box. I was able to exit the Rhix conversation, but then later when I tried to turn in my "bless the bodies" quest in Helm's Hold, I got stuck...I couldn't escape the dialog box and had to completely quit out of the game.