Aha, yes, the trimming is what causes the problem. Our database only has the CRC's of untrimmed ROMs, because keeping a list of trimmed CRC's isn't really feasible (there would have to be a CRC for every possible way a ROM was trimmed, all of which can cause marginally different files but completely different CRC's). If you happen to find an untrimmed version (not sure if it's possible to un-trim a trimmed file) and it still doesn't work, do let us know. Again, many thanks for your help.