And did you save the setting before exiting the bios?, more than likely you may of forgot. Because I just cannot see how in the boot order of the bios if you set it for example to the dvd drive as the first boot able device it fails to see the windows DvD. Are you sure you have a windows disk that can boot from Dvd, does it have a boot loader. The fact it keeps looking for the boot manager of the last windows Os says you have not saved the setting in the bios once you have changed the boot order of devices. Make sure you are saving them after the changes you made, then exit the bios.