So I have a Toshiba Satellite C855D-S5303 that has had windows tech preview installed on it. But when I tried to boot into it, it said that the windows signature wasn't correct and it would continously going into that window. I then tried to install a newer version of the tech preview and ubuntu, but neither succesed (they were on usb.) I also tried to install Windows 7 by a disk, but that didn't boot to either. I pressed F12 to boot into the boot order, select to boot into usb or disk and neither worked. I set usb to the first option and it didn't even boot to the usb. It might be the usb's that might not be bootable fully, but on my win7 pc i got all of them to successfully be read as bootable. I booted into the bios serveral times and set the boot mode to CSM mode and UEFI mode but neither would boot from the usbs or disk. I have the InsydeH20 Setup Utility BIOS on my PC. Any support that could help will be great! Thanks, Mrti.