i had the same problem, i could load ea games fine and even boot non-ea games but booting non-ea games with the ar2 would end up in it freezing at that screen after i press x.
this is the way i do it now, and if timed right works every time for me
get to the screen - after start game -> without codes, eject the ar2 cd and replace with backup. then close tray - wait a few seconds and you'll here the ps2 spin the disc a bit, if you try it once you will hear it spins up a bit and then at the end it makes a different souns. if you press x just before the last sound it will start.