I was already running 13.10 alongside Windows 8.1 with no problems at all. I upgraded to 14.04 LTS yesterday through software updater yesterday and now the Windows boot loader on the Grub menu doesn't work. It just goes black for a second and then returns to the Grub menu again. I should probably add that Windows was pre-installed, so no DVD.
Any help would be greatly appreciated. I am a Linux newcomer, so go easy on me if this is a really obvious fix. I would get rid of Windows entirely but my girlfriend refuses..