I installed Ubuntu 13.04 in a new partition on my HDD alongside an existing Windows 7 installation, but I'm now unable to boot up into Windows 7 from the GRUB menu. Initially I was unable to select the Windows 7 loader partition from the menu at all, as my keyboard would not activate at boot before the selection defaulted to Ubuntu.
Having gotten past that issue, highlighting and selecting the Windows 7 partition from the menu only darkens the screen before returning me to the GRUB menu again. I don't get any kind of error message or warning, it's simply as if nothing has happened or the Windows partition simply isn't there. All other functions on the GRUB menu appear to function as they should. I can boot into Ubuntu without any problems, but Windows appears to be entirely closed off.
Edit: I have tried Boot Repair, the problem persists.