a Dissidia: Final Fantasy you say? you just need to update to 5.00M33-6
just download the 5.00M33-6 and 5.00 OFW from here:
Custom Firmware 5.00 M33-6 Released, PSP Hacks - PSP Slim Hacks.
Easy Steps:
Take the UPDATE folder with the eboot inside folder from 5.00M33-6 and put it in the ms0:/PSP/GAME/
make sure it is in caps.
Now take the 5.00 OFW and re-name that eboot to 500.pbp
Put 500.pbp in the same folder as UPDATE.
once you have those steps above done, its time to install.
On your XMB, go to Game, and under that there should be a memory stick, go to that.
Select the 5.00M33-6 Installer and then it should run.
Follow the instructions the installer tells you to do, it should be safe and simple. DO NOT interrupt the installer once you have started.
Once complete, it may ask you to reboot by pressing any button. Do that.
You should now have 5.00M33-6. You can check in the system info(i assume you already know).
If your not sure:
ms0:/ is the memory stick drive, which should be something like E:/ or G:/
OFW is Official Firmware.
the folders have to be in CAPS.
XMB is like the dashboard of the PSP, basically the main menu of the PSP.