You can check
this thread to see if there's anything in it that can help you, and if you haven't gotten the downloadable content yet, I think it has a patch in it too. It's free, and works with Steam now.
To get the downloadable content, you have to follow the steps
here. Your CD key is located at \HKEY_LOCAL_MACHINE\SOFTWARE\Electronic Arts\Electronic Arts\Mass Effect (tm)\ergc