Okay some more info for the guy who started the thread...
I had the same problem, Was freezing all the time... even when I took my back-up from a few days ago! Since this was my real account and I have spent almost 3 years building that garage I was super sad to think I had lost my cars... I deleted the GAME DATA (not my save data) and spent almost 5 hours updating and re-installing GT5. In the end I am up and running again. Not sure what happened but that is what fixed it for me and in the end all my back-ups were fine