PC will boot into Windows 7 when there is a bootable DVD inserted, but not without it

According to the picture

your HDD will fails soon because you have some uncorrectable and some pending sectors. The BIOS seams to detect this during boot:

 "Test failed. Drive replacement recommended. Completion Code: 7"

and skips the HDD, but still allows you to boot if you ignored a different boot drive like a DVD. Backup all data to a different drive and replace the HDD with a new one.

If you still see the issue after replacing the HDD, load the default BIOS settings, maybe the BIOS stores the error information and this error log must be cleared.