Since the last patch I've had two lockups. Both times I was in a furball and the program hung with the sound looping.
I could then hit the Windows key and bring up the taskbar and start menu and halt AH. I've not had a lockup with this 9 month old PC until this patch.
I'm getting a fair bit of stuttering too, since I installed the latest high res pack. Was OK with the old high res pack though.
PC has a 6600 CPU, 6600 GTX video, 2 GB RAM, Audigy soundcard and Win XP.
When I get time I'll have a look to see if any settings were altered with the new patches, I've not altered anything myself.