I have downloaded a CSO file to play on my PSP 3000. I created a new folder called ISOCSO, put the file in it, and put the folder into my "GAME" folder on my PSP. It didn't show up. I also tryed putting it in the PSP, but it said that it was corrupt. I have firmware 5.51 installed. Youtube had a few videos showing that playing ISOs and CSOs can be done on the 3000, even without a pandora battery. Should I try an ISO file instead? Should I downgrade to 5.03? I am new to PSP, so if anyone could tell me what I need to install etc.. that would be great