I had a similar error when I used the elevator on the Leviathan. It would save, then stop. I tried switching between my CDRW and DVDROM drives, restarting the computer, and loading an earlier game. The solution was actually very simple. All I had to do was load the autosave. I hope this works. Let me know what happens, please.
I support "No Child Left Standing
I have Attention Surplus Disorder.