Mountain Lion Installation Error Messages
For those that aren’t using a dual boot system things are fine. In this case things are a little troublesome. Soon as we have more information on what to do i’ll update the article.
This disk doesn’t use the GUID Partition Table Scheme. Use Disk Utility to change the partition scheme. Select the disk, choose the Partition tab, select the Volume Scheme and then click Options.
IF you get the “This disk doesn’t use the GUID Partition Table Scheme.” error from what I can see it’s a case of formatting and starting again but at the moment there’s no clear way to make a USB Bootable Mountain Lion Disk without going down the restoring a partition route. InstallESD is missing in action on the Golden Master.