Reboot and select a proper boot device error?

I just built my own desktop computer and finally got it running. I installed windows 7 on it yesterday and transferred all of my files to it. It worked perfectly and then I put it into sleep mode. It would not respond so I restarted it. Now my computer will not boot windows 7 and says "reboot and select a proper boot device error." I have changed all of the bios boot order but i'm not sure if it is letting me save my settings. Either way I can't seem to fix this error. What can I do?