Ah, so apparently Fallout 3's latest DLC is just racked with bugs and issues. I'm browsing the TRIO of threads on the Bethesda Forums now, and it seems that known issues are a lot of missing textures and meshes, game freezes, among others. The forum community is guessing that the bugs are coming from either the file becoming corrupt when it was put up on XBOX Live, or issues resulting the the massive amount of info-suck generated by all the people downloading it at once. They're also suggesting waiting a bit, and then downloading to see if the issues resolve themselves. Re-Downloads may also be necessary.
It makes me glad that I didn't stay up late into the twilight to get my Fallout fix. Oh well, I'll wait till later tonight and see if things haven't been resolved.
18 hours ago