Problem with my FF3 can anyone help?

[redretro]

ok im playing a NTSC version of FF3 on my PAL SNES using the converter. the snes and converter work fine as all other games have no trouble

but with FF3 eveything started out ok then after about an hour the option screens fror equiptment, relics, items and skills appear black and i cant see anything. the other saved games on the cart have the same problem but everything else works fine and it was working to start with, any ideas?

[redretro]

someone suggested deleting the games and starting again bit as far as i can see there isnt a delete option and if i start a new game and save over the old 1s it still happens after a while

[Pullmyfinger]

Can play an hour, get the glithched menu, turn off the SNES, play another hour, rinse and repeat?