I would back-up my save onto another hard drive and delete both of the saves from the PS3. Start up GT6 offline and see if it works with a new career/save. If it works, then do what you choose from there. If it doesn't work, I'd delete the game data and re-install the updates (keep the save from the external hard drive) with no saved data from GT6. You'll lose your replays and images, but I think you can just save the replays and export the images. Like I said though, do what you choose. If you feel the need to delete the game data, then do some research about the lost replays and saving then recovering them.
haha Whaaaat.
Edit -
I've only had my PS3 freeze once well over a month ago. I've had a couple of hangs as well.
After this update the loading times between screens are noticeably slower. They were just about seamless before the update.