3.10 O.E problem

I have a problem with my 3.10 O.E Psp, I recently upgraded the firmware to 3.40 O.E and found that most of my game isos no longer loaded, I recovered back to 1.50 firmware useing the on button and the R trigger and reinstalled the 3.10 O.E only to find that the problem was now affecting this firmware too, There were never any problems before? does anyone have any ideas?

go to revovery mode and tweak some of the iso options ( power off, right trigger on boot up)

I have found the settings in recovery mode that caused the problem, it was the execute boot.bin in the advanced settings. Now playing with my 3.40 OE psp with a smile on my face again. Many thanks Chameleon, you sir, are a star.