Hopefully someone might be able to help me, kinda pulling my hair out now (what I have left anyway!). Last night I upgraded a Windows 7 Pro install to Windows 8 Pro and activated by KMS (happy days!). The problem is now that I cant seem to upgrade to 8.1. I have managed to install with the default Pro key up to a certain stage at which point during an expected reboot it returns me to the Windows 8 desktop and says that a problem occurred and Windows 8.1 cannot be installed. Has anyone else experienced this before or know how to solve the problem? Any help is greatly appreciated.