Are you playing off the DVD or is the game installed on the hard drive? You can try installing it, if applicable, and see if that makes a difference, but there are not a whole lot of options you could try adjusting in the Xbox version to see if they made a difference.
Try emailing support@larian.com, with a description of the problem and maybe a link to this topic.
See Lar's post
here on how to send them an Xbox save.
