I bought a TA-082 psp that came with version 2.71 firmware. I downgraded it version 1.50 with dark alex's downgrader with HEN-D. Then I put a ".cso" format game in the "GAME" folder of the memory stick. It didnt show up on the Cross Media Bar so upgraded to 3.40 OE-A using dark alex's software. The cso file still didnt show up so I installed devhook v.44 onto the psp using "Ultimate Installer USB Edition v0.3.1 (UI).exe which automatically did everything. I noticed a new folder in the root menu named "ISO" so I put the cso game in there. Now the game shows up on the Cross Media Bar yet when I run it, it says "The game could not be started. (80020321)" I then found out that devhook v.44 doesnt work with 3.40 firmware. Now, I would like to start from scratch before I downgraded it so that I can get rid of unnecessary things from my memory stick. Also, do I even need devhook to run cso files? Thank you in advance.