You have tried to access a disk that is incompatible with the current version of your operating system. This could be because it was created under a previous version of the system or it could have been created under a completely different operating system. You would also receive this error if you tried to load a disk with a name that clashed with a disk that was already loaded.
Resolution:
If the error is a result of a clash of names you can rename one of the disks and then you can load both disks together if this is what you want.
