not a bootable disk

Hi everyone, This post is similar to https://forum.proxmox.com/threads/boot-failed-not-a-bootable-disk.39301/ and https://forum.proxmox.com/threads/boot-failed-not-a-bootable-disk.11788/ These forum post are unresolved. I have a VM running Linux Centos 6.7, 64-bit. 4GB RAM, and only a 32GB...