anyone can help me
i'm just download sony new version 4.00
but i cannot play any of cso/iso file..

anyone who had an idea can help me
thank you

You need to research Pandora's Battery and Magic Memory Stick. That's the only known way of downgrading from 4.00 and installing custom firmware which will let you play ISO/CSO files.

ADW is 100% right, you will not play a downloaded game on OFW.

luckily you can still change your fw to cfw using the pandora battery... good luck

yo need custom firmware, i recommend making Pandora battery and downgrading your psp that is the only way to downgrade i think at the moment.

first u need to buy a extra legit battery to create pandora, buy a 128mb memory stick pro duo too. Convert them to pandora battery and Magic memory stick and u are good to go.

when you have an official firmware installed, you cannot play CSO ISO games... You have to downgrade it to a Custom FIrmware version...

Use a Pandora battery to downgrade that 4.00 to install custom firmware