Due to a conflict between the game and the hardware on the newer Slim PSPs, you may have trouble playing some PSP games on the Slim line PSP. The game was coded for and will work flawlessly on standard PSP units however. We apologize for the inconvenience.
Start the PSP without a disk
Goto "System" --> "System Settings" --> "UMD Cache".
Set this option to Off and then try the game again.
If the problem happens again, then we can only suggest playing this game on a normal PSP.