I have a psp of 3.40 oe-a cfw. I recently downloaded games from a site. When i downloaded the game from the site it was in .cso format. I put it in the ISO folder in my psp. I went to my psp and i saw the game there. When i play the game it starts off ok then it tells me this error. I downloaded 3 games and the same problem occurs. The intro of the game works fine but the actual game doesnt work. I dont know what the problem is.