I had a similar problem: launched the game, played for a while, then it freezed with no possibility of restore.
I have a Radeon 9500 Pro and the cause was the Omega 4.12 Beta set of drivers.
Removed them, installed the new official Catalyst 4.12 (final) and then all worked fine. No problem at all.
Try to change or reinstall your video drivers, it could help.