This requires to go into Bios in the computer. Restart you're computer, and from the start hit these buttons., ts s usually alt right after it shows the Toshiba logo. Right alt to be exact, or press the F12 button, or F1. Firstly you need to understand and diagnose you're problems, you said it doesn't detect any usbs, or hard disks with you're desired os, but it loads them up fine when you're fully booted, you're pc does in fact detect it, it just cannot boot into it. Usually its a boot mode. A boot mode is a mode to boot from or install another os, that is compatible. Depending apon which ones you have, like uefi mode, or another, change it the other options. If it works it works, it all really depends. However i would suggest wiping your harddrive of your current os your on. Because if not you probably do not have enough room to install, but if you do you'd make a duel boot. Now remember, if you change from the boot mode you're os was installed onto, it cannot boot into it. So keep that in mind, let me know how everything goes, and i hope i helped you!
