My laptop SVS Vaio come with preinstalled Windows 8 pro x64. I prefer Windows 7 and try to install it on the Vaio. But Windows 7 x64 cannot boot under UEFI mode. Booting progress hung up at splash screen (flying logo of windows 7 boot) while boot under MBR mode are OK. Disable or Enable secured boot from BIOS does not effect. Need any idea that can help. Many THX.