You wrote that always stops at 25/33%, so on that area of your time-line may be some corrupt media, or may be the very project corrupted.
If there is some corrupted media, you have to find out which is the corrupt clip or still that is causing the troubles (do you have any MOTION project on your time line?),
You must to put the media off-line and them relink by bunches till you get in troubles again.That means that you have try to relink the faulty media.
There is not other way to do so.
If the problem is on the project file, you need to open the project with the media off-line and save with a different name.
ANYWAY, before trying any of both methods, you should try to clean FC Preferences.
Run this free application:
http://www.digitalrebellion.com/prefman/
rafael