Windows 7 'Reboot and select proper boot device'

[BigRoy77]

Months ago, when I was dual-booting Windows 7 and Ubuntu, I started getting that 'Reboot and select proper boot device' nonsense, which wouldn't go away no matter what I did--until I discovered that putting the Windows recovery cd-rom in the dvd drive would prevent it, even if it didn't wind up booting the machine. (I didn't 'press any key to boot from cd-rom'.) Now Ubuntu is gone, cause I never used it, but the message remains. None of the other posts seem to mention the 'cd-rom in the drive' thing. But how can I get my machine back to normal?

 

[RealBeast]

Start up from the Windows installer disk and do a startup repair with only the OS drive and optical drive attached (no additional storage drives or USB sticks). That should fix it, but if it persists read THIS for using Bootrec.

 

[BigRoy77]

Start up from the Windows installer disk and do a startup repair with only the OS drive and optical drive attached (no additional storage drives or USB sticks). That should fix it, but if it persists read THIS for using Bootrec.

Thanks, but I finally discovered that the wrong hard drive was in the BIOS as the boot drive. But how did that happen out of the blue? My Windows 7 was starting fine for over a year before that. Now more recently (just today), it suddenly rebooted itself (the default behavior for a 'system failure') and came up with the error again. Why did my BIOS settings change by themselves?