Independence Exploit...

An oldie but a goodie :)

Try using a normal thumb drive. It may be that the PSP is simply not supported.

I used Codebreaker 9 instead of Gameshark.

Also if you want to play ISOs get a "chubby" (old) PS2 and hook up an IDE hard drive using a network adaptor.

You may not be able to play online but its MUCH more convienant to load ISOs from the hard drive.

I wish I still had my PS2.