I have the EXACT same problem. I'm going through episode 4 for the first time, I approach the news stand at the harbor and I get... "save data corrupt. will recreate". the PS3 then freezes. I have to manually reboot the PS3 and now all my saved games are gone!
Thats hours of my time GONE. What kind of morons are working on this game that would allow this kind of bug to happen on a full release. Havent you guys heard of beta testing? Of course not, lazy programmers like you dont bother and just let the public at large be your beta testers without the common decency of letting us make the choice. Its pathetic that companies employ people of this caliber. If they were in my employ, they would not be in my employ.