I'm trying to install Ubuntu on an E-series Vaio with windows 8 pre-installed.

To do so, first I shrinked windows 8 partition (using the windows software). Then I burnt a 64-bit Ubuntu 13.04 Live DVD. I disabled Secure Boot and Fast Startup (not UEFI).

I had problems with the installation, as afer selecting the install option the screen started to flash and flicker. I solved it using nomodeset and installed it. I made an 8GB partition for swap (as that's my RAM capacity), a 20GB one for root and a big one for /home. I wasn't sure if I had to make any of those primary instead of logical, but the installation ended correctly.

When I start now the PC, GRUB loads and shows me both windows 8, Ubuntu, and the Vaio system setup. BUT , if I select Ubuntu, it boots (I can hear the ubuntu welcome sound) but the screen flickers and flashes. I tried to use nomodeset, but that somehow starts Ubuntu in text mode (terminal). And if I choose Windows 8, it says that "drivemap" couldn't be found. "invalid EFI file path". The system setup boots correctly.

I'm a n00b, and I'm really lost. Help, please!