After I get Poquelin to open his dimension door and everyone gets transported to Easthaven, the game locks up. Everything on the menu is greyed out. I can however manipulate the dialogue screen, and time does pass since my buffs all expired while I was waiting for the game to come back.
Does anyone have any ideas on how to fix this?

Is the game patched???

No offense, but why are you posting here? I mean, we love games and all but this is a pretty general forum and the game isn't even on GoG (yet?).
Try gibberlings3 forums or any of the other active infinity engine communities out there. Here's a link to the gibberling3 LINKS page, which lists most of them (the ones besides itself, obviously):
http://www.gibberlings3.net/links.php
I trust you can find your way from there? Good luck.

Ah, excellent! I tried a couple other forums for IWD but the links were dead. I'll check this one out, thanks.