USB boot not working, loop of error messages

[VirusZParadox]

I have a computer that I just built, and I have a USB with SteamOS on it. I'm trying to install steamOS to it but when I inserted the usb device, changed boot priority and rebooted it has started giving these errors.

It tells me to remove any disk or other media, then when I do so

Then when I do that it tells me to reboot and select the proper boot device or insert boot media in selected boot device and press a key.
Then if I follow these instructions it gives the first error again, etc.

I'm not sure I fully renamed the USB partition to SYSRESTORE like the SteamOS instructions say, or I didn't change it to UEFI. I can't get to the BIOS to change that though.

I have an ASUS M5A78L-M Motherboard.

 

[C12Friedman]

It sounds offhand as though your OS image is bad. I'll suggest reinstalling the OS image on the USB device and trying again.