PSP 3.40 iso problems?

Ok i have a psp 3.40. I havent palyed for a while but i used to be able to plays all sorts of isos. now when i download them i get multiple errors. I dont think they are bad isos because i tried many different ones. one problem is the screen goes black and freezes. another is it goes black and turns off after a little. the third is the stupid error code thing. I have disabled all options in recovery mode. Please tell me whats wrong and if you know the proper settings i should use. oh and i tried the umd thing multiple times. winner gets 10 points.