I have noticed the following issues on Xbox 360 since I have downloaded Dawnguard.

1. I cannot purchase the alchemy lab for Breezehome. (I was able to purchase the bedroom decorations but not the lab). Tried reloading, buying the stuff individually and together. Nothing worked no lab.

2. Game is crashing approximately once every hour or so, particularly on auto saves. This is a 300-400% increase in crashes since the download of DawnGuard. (This is happening on both high level and lower level characters).

3. Inability to shift between first persona and third person view on a high level character.

4. Character goes completely invisible in first person view (no weapon or shield visible).

This is all that I have noticed so far.
[Edited for spelling.]