Able to Boot from Win7 disk but not HDD

This morning my PC failed to boot after a re-start. Repair/Restore did not work. I set Bios to boot from CD-Rom and inserted original Win 7 disk. Booted fine and everything looks as if noting happened. Performed Scandisk, Diags, Created an Image, defrag HDD(But it was not needed). Removed disk, changed BIOS to boot form HDD and No Joy! Set Bios to Boot from Disk vs, HDD and here I am...