I understand what you are doing. I know that you are using ISOs. If the image has not been altered in anyway and it was properly mounted the installer should not see any difference between it and the physical disc. Like I said, it is not recognizing the image as the right disc. I am trying to figure out what is different. The installer was designed from the NA release. Other versions may be different enough for the installer to not recognize it. If it is, say, from a European release that would explain it. If it is a Slash re-release, it may be different enough for the installer does not recognize it.
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