I've had this happen (with small files) and after re-building the scenes from scratch was able to render them fine.  I thought the file(s) had somehow got corrupted.  Are you able to load the scene into a text editor and scan for errors?  Do you have earlier versions of the file?

Somethings you might be able to try is changing your render settings, clearing away any cache files and/or temp files.  I know I still have hair sets that don't play well with certain of my saved light sets.  Some combinations simply can't be rendered with my current setup.  You say you've rendered the scene before so I think you don't have that issue here.

Maybe someone else will come by with some suggestions.  Best wishes,
Rªnce