I have an HP Pavilion p7 1010 with 10GB RAM that's dual booted with Windows 7 Home Premium and Ubuntu 14.04. I tried upgrading Windows 7 Home Premium to Windows 7 Professional, and it said that it did it successfully. But for some reason, it didn't recognize my product key, so I tried to go back to Windows 7 Home Premium using the Recovery Partition. That didn't help solve anything, but when I rebooted, it gave me a message that said "Error: No such partition." It said GRUB Rescue, so something must have happened with the Linux bootloader.