Using Lion's DU. Trying to erase a Sno Leopard partition on an external HD (to clone Lion to it via CCC). The external has not been problematic.
In DU, I select the external and select the Sno Leopard partition icon. Click erase. Get the message: "Volume erase failed with the error: POSIX reports: The operation couldn't be completed. Operation not permitted".
Before trying to erase, I started CCC cloning to the Snow Leopard partition. Then thought better of that and stopped the cloning after two minutes. Then tried to erase and got the failure message. Tried again to erase, and the same failure message recurs.
