Thanks, guys for testing. I suspected it wont work. If it were that easy then only fix would have been posted. Like Duplex release of Driver: San Francisco - works only PSN version, right? Just like mod632 said - retail and PSN games are signed totally different.
On a NATEPIGs note: Very strange he cant make the game working. It's tested on 3.41 and 3.55 and it works flawlessly.
Something must be wrong with your PS3 setup or corrupted download. Do you have ReactPSN installed maybe? You must provide with more details.