PSP games cso Iso problem?

ok, so i have a tekken 6 iso and it works well. then i thought of downloading a cso version because so i can save some space. after i played the cso version to test it for awhile, then i switched back to the iso version. now, the gameplay freezes. its just constantly loading forever like "Now Loading" and it doesnt go to the game. how do i fix this?