I was installing Proxmox 4.X on my new server systems having SAS disk with LSI MPT2 Raid controller. The installation went just perfect, however, after post installation boot- I was getting errors as below similar screenshot-

After googling a lot, found the solution. Here goes it-

1. On the initial boot screen- select “*Advanced…..”
2. Hit “e” on the next screen
3. You’ll find something similar as below-

   title Debian GNU/Linux, kernel 2.6.26-1-686
   root (hd0,0)
   kernel /boot/vmlinuz-2.6.26-1-686 root=/dev/sda1 ro quiet
   initrd /boot/initrd.img-2.6.26-1-686
   add rootdelay=90 after quiet

4. Hit “Ctrl+X” or F10. The boot will initiate and you;ll have the login prompt appears on screen. Success!!!
5. Now, let’s make it permanent for the next boot.
6. now open /etc/default/grub and add the following command-

7. GRUB_CMDLINE_LINUX_DEFAULT="quiet rootdelay=90"

8. Save it
9. Now issue the command-

10. update-grub

11. Now time to reboot

Problem resolved!!!