Just so you all know I haven't tried this myself yet since I got so pissed at the game that I haven't played anything since then lol.
My friend told me to try this, (do it at your own risk)
This might work but and if any of you tries it and works let the rest know!!
If you have a formated USB drive, you copy your game safe data from the PlayStation to the USB drive, then from the USB data you try to start the game and override the current safe data with an older safe data in your game before the error, forcing the game to restore and sync up with the old safe file.
The Steps are:
*Go setting
*Then application save data management
Once there
*Go to need for speed file and you will see the game safe data there.
I think you might not need the USB if your game is already on a external drive but once you are in the NFS file try to force the the game to start with an older file, and if possible delete the file with the error.