Not a fix, but I thought someone might be interested in it. This is how to get the DLC temples and Altair outfit. *Please note: you must be using an offline fix to use this.*
1. Go to C:\Program Files\Ubisoft\Ubisoft Game Launcher\storage
There will be another folder in there so open that. Now there may or may not be another folder, if there is open that, if not, don't worry.
2. Download this:
Mirror 1: http://www.megaupload.com/?d=Z60X8ENH
Mirror 2: http://www.4shared.com/file/KwamyB9X/AC2_DLC_Enable.html
3. In the zip is save game data.
If you have played the game before you may already have saves in the folder you are in. Even if you haven't saved in all the slots in-game, the game does not always save in order, so check the size of the saves. The largest will have save data in them. If the one that has save data in is the same as the save number in the zip, just rename the one in the zip to the next number. Then copy the saves into the folder.
If you haven't played the game just copy the save into the folder.
Start your game again, load any save, or start a new game and you will now have the content.