A couple people did mention their game locking up at that point (in the topic Monty Python
Did you try reloading? Maybe skip through the preceding conversation, rather than letting the dialog end on its own (that helped for a cutscene in D2:ED that that some people had trouble with, though in that case the cutscene immediately followed the conversation).
On the PC you could try quicksaving and then quickloading, and see if that gets your character unstuck. Temporarily lowering the graphics options and game resolution might help, as well.
Try emailing email@example.com, with a description of the problem and maybe a link to this topic. See the appropriate support page for DKS