Hi,

I have load another disc for the new monster but when I change back to Monster Rancher 4 DVD it says this is not Monster Rancher 4 how can I do?

Thanks

Are you sure you are putting the MR4 disc back in when it says to? Also, check for deep scratches on the disc itself. This may cause the reading error when trying to generate monsters. Scratch Out! is a fairly good product to use to mend deep scratches.