Try this first..

1. Boot from CentOS installation disc (for example, CD #1 or DVD).
2. For CentOS-4 or CentOS-5 type "linux rescue" at the "boot:" prompt. For CentOS-6 pick "Rescue installed system" from the boot menu.
3. Mount all filesystems in read-write mode.
4. Change root to real root ('/') on your hard disk:

5. # chroot /mnt/sysimage

6. Re-install bootstrap code (GRUB).
• If you wish to re-install GRUB to the MBR on a SCSI or SATA disk (/dev/sda):

o # grub-install /dev/sda

• If you wish to re-install GRUB to the PBR of Partition #2 on a SCSI or SATA disk (/dev/sda2):

o # grub-install /dev/sda2

• If you wish to re-install GRUB to the MBR on an IDE disk (/dev/hda):

o # grub-install /dev/hda

From: app_rpt-users-bounces@ohnosec.org [mailto:app_rpt-users-bounces@ohnosec.org] On Behalf Of John (WB5NFC)
Sent: Friday, February 03, 2012 11:21 AM
To: app_rpt list
Subject: [App_rpt-users] ACID Boot Error Help Request

My trusty Acid server bit the dust last week. This is full-size Dell with plenty of horsepower and a quad radio interface, not my BeagleBoard.

The computer goes through POST with no errors reported, then:

grub loading stage 2

GNU grub V0.97

[Minimal BASH-like line editing supported. 

I think this happened after a brief power outage, but I'm not sure. Just just noticed the nodes were down and then found a computer that would not reboot. 

Suggestions for troubleshooting, please?

John / WB5NFC