I have read all posts on this and this computer is too old for any to be applicable. this is a Toshiba satellite 2435-s255. When in BIOS there are no options involving a UEFI change, or secure start change. I have changed the boot options to USB, it just doesn't seem to care. The usb worked fine on my new laptop, went to windows installation screen, and the Toshiba windows xp SEES the usb and it's contents, but will not boot from it. I am trying to upgrade from xp to win 10. I thought about formatting the drive and trying to see if it will then see the usb but would like to not mess it up worse than it already is. I have already changed the startup to external devices in the system BIOS settings, and hit F2 to try booting from it there...The BIOS has no settings that I have read about in previous posts, and I've already pulled out half my hair trying to figure this out. If anyone can help I'd GREATLY appreciate it but it's looking like a lost cause here. You are my last resort, please help!