Just lost my entire game (spoilers)...

[LadyDonut]

Had been having the same issues as some other users - game kept crashing to desktop between levels. I put the graphics on low and put antivirus software on silent and got through most of the game without too many issues. After I finished sabotaging the steam regulator and ran through the streets to reach the elevator and go back down into the machine, the game crashed between levels again. I opened the game back up, selected my profile and tried to load the game again... and it's taken me right back to the opening sequence. My whole game is lost! Please help!
Playing on a Sony Vaio (Laptop) with Windows 7
Intel core i5
Radeon graphics