12 : Invalid device requested.

This error is returned if the device strings syntax is correct but other than that, an error occurred that isn't defined by any other error.

Solution

When you installed grub in your boot record using the interactive commands, did you execute the two lines below in the grub prompt?

Code Listing 3.2: Interactive installation commands

grub> root (hd0,0)
grub> setup (hd0)

(hd0,0) must be replaced with your boot partition and (hd0) with the HDD you have chosen. Remember that (hd0) will install the bootloader in the Master Boot Record of the first hard disk, the primary master.

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scrivendo questi 2 righi cosa succederà?
grub> root (hd0,0)
grub> setup (hd0)