Why a computer a message re boot select a proper device?

[sureshrajbhar]

Hello,
WHY A COMPUTER DISPLAY A MESSAGE SELECT A ROPER DEVICE AND RE BOOT

 

[rolli59]

Then it is trying to boot from a drive that does not have a bootable disk. Possibly a CD left in an CD drive or floppy in a floppy drive and either of those drives before HDD in the boot order.