It seems on the Lenovo (and all UEFI systems?) Windows is not anymore booted through the nt loader but through an efi boot loader residing in the efi partition.
I can assert that some EFI systems are not affected by this. My Windows 8 install on an ASUS F2A85-M can be booted from the GRUB entry, which is similar to the one GRUB generated for Dieter.