You say you cannot boot from a CD_ROM, so I presume you have placed that disk (maybe a Windows Install disk?) in that drive before powering on. The error message you see is generated after the BIOS tries to boot from the HDD that is not bootable. So, it appears somehow that your BIOS is NOT set to boot from the optical drive. You need to find the way to enter BIOS Setup - there is usually a particular key you must hold down while you turn on, until the Setup menu appears. Then you can go to Boot Priority Sequence and set it to try the optical drive first, then the HDD.
One small thing to check. Any chance the optical drive is just dirty inside, and so it cannot read the CD_ROM? You can get an optical drive cleaner disk and try cleaning it first.