I recently built my first computer and am planning on installing Win7 from usb. Upon starting up, I received the message 'Reboot and select proper boot device or insert boot media in selected boot device and press a key'. I have tried everything every way and cannot for the life of me enter the BIOS screen. Some keys on the keyboard don't do anything, some keys make the message show up again, and Ctrl Alt Del just restarts the computer. I have an MSI 970A-G43 MoBo. Please help, I appreciate it.