"No bootable devices" msg, but can boot using f12

I get the "no bootable devices" on booting, but can boot successfully into Windows 2000 if I pick the hard drive by using the F12 key when booting. Hard drive is in the Setup listing of bootable devices (I moved it to first on the list). Computer is a C600, vintage 2001, bios version c21, running Windows 2000 Professional.