I recently dual booted my sony VAIO having pre-installed Windows 8 with Ubuntu 12.04 using a liveCD, and Ubuntu worked fine. (I had done the needful as seen in Installing Ubuntu on a Pre-Installed Windows 8 (64-bit) System (UEFI Supported) and Ubuntu was working perfectly) By the way, I had pre-partitioned my Windows C:drive and during booting I just selected "Install Ubuntu along with Windows 8" and did not ask for any partitioning!. After installation, I even got the option to select windows or ubuntu during startup but windows wouldn't boot on being selected. So I selected 'boot repair' as shown in the link (using recommended settings and all). An option came there to remove grub and reinstall it. Everything went fine and I rebooted only to find:
GRUB loading error: invalid arch independent ELF magic grub rescue>
on typing ls
I get points like (hdX,gptY). I have found my file lies in (hd0,gpt12) but insmod linux does not work. On starting with my liveCD, nothing happens, I cannot boot from it and I get the previous screen only. Please help!