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When you copy a game to your psp and it is a 6.20 version It always says corrupted data when its a ISO file

When you copy a game to your psp and it is a 6.20 version It always says corrupted data when its a ISO file
That sounds right to me. You need to downgrade your custom firmware to a lower version. Find out how to do this at http://www.wonderhowto.com/how-to-run-cso-file-2-psp/