Hmmm, try a different copy (go to the store and rent one). Or get one from a friend. You could try uninstalling the game (deleting the game data) but keeping your save file and see if that helps.
If none of those work, you might have to do a system restore. This really isn't as bad as it sounds because you can back up anything on your HDD on an external drive, i.e. a flash drive or an external HDD. You can just keep your saves if that is all you care about. You can redownload anything on the PSN up to 5 times (excluding Warhawk and possibly GT5 prologue).
If THAT doesn't work, you are just plain screwed.
We had two bags of grass, seventy-five pellets of mescaline, five sheets of high-powered blotter acid, a salt shaker half full of cocaine, a whole galaxy of multi-colored uppers, downers, screamers, laughers…Also a quart of tequila, a quart of rum, a case of beer, a pint of raw ether and two dozen amyls. The only thing that really worried me was the ether. There is nothing in the world more helpless and irresponsible and depraved than a man in the depths of an ether binge. –Raoul Duke
It is hard to shed anything but crocodile tears over White House speechwriter Patrick Buchanan's tragic analysis of the Nixon debacle. "It's like Sisyphus," he said. "We rolled the rock all the way up the mountain...and it rolled right back down on us...." Neither Sisyphus nor the commander of the Light Brigade nor Pat Buchanan had the time or any real inclination to question what they were doing...a martyr, to the bitter end, to a "flawed" cause and a narrow, atavistic concept of conservative politics that has done more damage to itself and the country in less than six years than its liberal enemies could have done in two or three decades. -Hunter S. Thompson
