thank you for the prompt response! i tried changing the names to lower case, but to no avail, i am booting all my roms off of a usb drive, and all the other roms besides psx work fine. when i put a psx game on the sd card, it works, but when i put the same file onto the usb and try, it returns to the ES screen. i have the proper bios files in both the onboard bios folder and the bios folder on the usb drive