It sounds like a corrupt file (data.000) in the save folder of the save you are trying to load (or in the default Bd_act1_start folder if this is happening when trying to load the game itself).
Do you have any other recent saves that you can try? If not, can you start a new game, then save under a new name and load it? If the problem persists in a new game, backup your current saves and do a clean re-install of the game and
patch.
If you do have a recent working save, it may be easier and faster to re-do part of the game than to try to fix your latest save.
Check your messages (click 'My Stuff' in the top menu bar, then 'My Messages').
