ROMS seem to work randomly, fine one flash and won't boot the next. I tried reformatting, different OS's, etc.
you forget to say your configuration. you could try to disable region free and enable gennt3 mode option
How about to take some tursted roms collections like GoodSNES, GoodGen. I had similiar problems when my cart was badly formatted. I reached file limit during copying files to cart and after that many roms stops working (dmaged FAT?) You can format card straight on PC using FAT16 (or FAT32 if you have recent OS) with block 16kb or 32kb. Then copy roms using some subdirectories.
