I'm having the same problem again - The cutscene has no dialog or anything (none of them have so far) The doorkeeper guy looks like he's talking and then the movie just stops (like it's waiting for something...) This is exactly what happened with kira at the war council. I didn't get any sound for the death scene at Yorwick either but that one didn't stop...
I've tried bones' suggestion and run it with no sound accceleration and with environmental turned off
--==System==--
Pentium 4 3.00 GHz, 1.00 GB RAM
NVDIA GeForce FX 5200
Soundmax integrated digital audio