I have a windows 8 sony vaio computer with UEFI bios firmware. I installed Ubuntu onto my system into another partition.
Everything worked except when I wanted to boot wondows 8. The grub menu does not pop up on boot so I cannot select to boot windows 8.
How can I fix the grub menu to show up and show windows 8 as a bootable system.
Your problem is that your grub menu doesn't have windows 8 in it's boot list so I doesn't show up nor does it give you the option to boot your windows 8 partition.
Try runnnig the boot repair live disk.
(1) DOWNLOAD BOOT-REPAIR-DISK,
(2) Then burn it on CD or put it on USB key via Unetbootin,
(3) Insert the Boot-Repair-Disk and reboot the PC,
(4) Choose your language,
(5) Connect internet if possible
(6) Click "Recommended repair" (write down the output help file)
(7) Reboot the pc
If it doesn't work you can link the output file link into your question and I'll help you to fix it.
Arno van der Weijden's recommendation may work. Another is to try my rEFInd boot manager. You can download and try the CD-R or USB flash drive version risk-free. If you can use that to boot both Windows and Linux, try installing the Debian-package version in Ubuntu.
EDIT: If Windows is re-setting itself as the default boot loader, see this question and my answer to it: Windows 8 removes Grub as default boot manager.
