I have a Windows 7 / Ubuntu 12.04 64 bit dual boot system on a ZT Affinity desktop with an Asus motherboard. I had Windows 7 Home Premium on the primary hard drive and Ubuntu 12.04 on the second internal hard drive. System had no problems for the past 7 months. I took advantage of the $14.99 upgrade to Windows 8 Pro. I upgraded but now I can not boot into Windows 8 Pro. I can boot fine into Ubuntu 12.04. I did not uninstall Ubuntu before doing the upgrade. I just did the online download of Windows 8 Pro and then ran the upgrade program. The program ran, installed Windows 8 Pro, rebooted itself a couple of times but now can not boot. When I start up the computer I get choices for booting into the current version of Ubuntu, an older version of Ubuntu, the Memory tests and Windows 7. I no longer have Windows 7, since I performed the upgrade, but its my only choice for booting a Windows program. I select it but only get an error message from Windows Boot Manager that says Windows failed to start. I'm not all that experienced with computers. Do I need to modify the Grub or do I need to start over with the upgrade?