A "continuity bug" is flaring up issues for some users and they're also looking into a save game not getting created at the end of Witch Hunt.
"Unfortunately, there is a continuity bug that is causing issues with a subset of our player base. While this issue is not affecting the majority of people, it is still a significant issue that we will address," BioWare's Mark Darrah on their forums.
"Clearly, it was our responsibility to catch this sort of issue in the interaction of Witch Hunt with Dragon Age: Origins. Our team is doing everything we can to fix this in a timely manner so those who are affected can go back to enjoying Witch Hunt as soon as possible."
The team is also looking at save game issues and they're "very close to a PC fix now - beta testers should expect to have something tonight to test!" Once that's been "successful" then console versions get their patch sent to "MS/Sony for certification shortly after."
BioWare's other DLC that released the same day as Witch Hunt for Dragon Age: Origins didn't go without some trouble either as Mass Effect 2's Lair of the Shadow Broker got a. The PC file was 1.5GB of nothing but junk data.
Let's hope this Witch Hunt woe gets sorted quickly.