Dual boot Windows with Ubuntu 12.10 UEFI

I have recently bought a Lenovo thinkpad edge with Windows 8 preinstalled on it, and I installed Ubuntu 12.10

I mostly followed the instructions under 'General instructions' here: https://help.ubuntu.com/community/UEFI except I chose 'Something else' as an option when installing and then didn't create a new efi partition for Ubuntu, only one swap and one ext4 as root.

Problem: when I turn on the computer and it enters grub menu (i have grub2) these are the options:

• Ubuntu;
• Advanced options for ubuntu;
• Windows 8 (loader) (on /dev/sda4);
• System setup

and ubuntu starts up normally, but when I choose windows I get:

cannot find command 'drivemap';
invalid efi file path

However, when I alter the startup order in BIOS, options are: 1) Ubuntu, 2) Hard disk, 3) Windows 8 setup, so my hard drive, or Windows 8 setup be loaded first, Windows 8 starts up normally (without showing the grub menu)

I have found simmilar problems, and followed this instruction https://wiki.archlinux.org/index.php/GRUB2#Multiboot_in_BIOS

I found here Grub errors during UEFI dual boot for Windows 8 (can't find command 'drivemap') though I didn't directly edit the grub.cfg file, I edited 40_custom file in /etc/grub.d. I had some errors in writting though (they showed as I ran grub-mkconfig -o grub.cfg) so I didn't go through with it...

I shall appretiate any help. Mostly it concerns me that I cannot yet really pinpoint the problem.

You need to purge and reinstall GRUB this way:

1. run Boot-Repair --> Advanced options
2. go to the "GRUB options" tab, tick "Purge GRUB then reinstall it"
3. click Apply

Indicate the new URL that will appear if any problem.