I tried the live boot CD and boot-repair, also loaded the Desktop install CD, and it looks like all partitions check out OK. However, when I try to boot Linux (the only bootable partition on the computer) I get a blank screen.

Every so often the screen give me something akin to: Assuming write through cache Asking for cache data failed

it appears to start booting, then hangs. Ctrl+Alt+Delete shuts down the machine

The last message during boot is "STarting TiMidity++ ALSA midi emulation... [OK]"

I used boot-repair to generate a boot info report. One thing looks odd to me- it reports a missing core.img on /dev/sda1. Here is the full info:

Boot Info Script 0.61.full + Boot-Repair extra info      [Boot-Info August 2nd 2012]

============================= Boot Info Summary: ===============================

 => Grub2 (v1.99) is installed in the MBR of /dev/sda and looks at sector 1 of 
    the same hard drive for core.img. core.img is at this location and looks 
    for (,msdos1)/boot/grub on this drive.
 => Windows is installed in the MBR of /dev/sdb.

sda1: __________________________________________________________________________

    File system:       ext4
    Boot sector type:  Grub2 (v1.99)
    Boot sector info:  Grub2 (v1.99) is installed in the boot sector of sda1 
                       and looks at sector 18406911 of the same hard drive 
                       for core.img, but core.img can not be found at this 
    Operating System:  Ubuntu 12.04.1 LTS
    Boot files:        /boot/grub/grub.cfg /etc/fstab 
                       /boot/extlinux/extlinux.conf /boot/grub/core.img

sda2: __________________________________________________________________________

    File system:       Extended Partition
    Boot sector type:  -
    Boot sector info: 

sda5: __________________________________________________________________________

    File system:       swap
    Boot sector type:  -
    Boot sector info: 

sdb1: __________________________________________________________________________

    File system:       ntfs
    Boot sector type:  Windows XP: NTFS
    Boot sector info:  No errors found in the Boot Parameter Block.
    Operating System:  
    Boot files:        

============================ Drive/Partition Info: =============================

Drive: sda _____________________________________________________________________

Disk /dev/sda: 160.0 GB, 160041885696 bytes
255 heads, 63 sectors/track, 19457 cylinders, total 312581808 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes

Partition  Boot  Start Sector    End Sector  # of Sectors  Id System

/dev/sda1    *             63   307,339,514   307,339,452  83 Linux
/dev/sda2         307,339,515   312,576,704     5,237,190   5 Extended
/dev/sda5         307,339,578   312,576,704     5,237,127  82 Linux swap / Solaris

Drive: sdb _____________________________________________________________________

Disk /dev/sdb: 320.1 GB, 320072933376 bytes
255 heads, 63 sectors/track, 38913 cylinders, total 625142448 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes

Partition  Boot  Start Sector    End Sector  # of Sectors  Id System

/dev/sdb1               2,048   625,142,447   625,140,400   7 NTFS / exFAT / HPFS

"blkid" output: ________________________________________________________________

Device           UUID                                   TYPE       LABEL

/dev/loop0                                              squashfs   
/dev/sda1        11b4d633-7863-40b2-a6ca-da5f82c3ad0b   ext4       
/dev/sda5        cb8d65f4-8cf9-4088-b804-e3dea2151033   swap       
/dev/sdb1        349E7C109E7BC8BE                       ntfs       Personal1

================================ Mount points: =================================

Device           Mount_Point              Type       Options

/dev/sdb1        /media/Personal1         fuseblk    (rw,nosuid,nodev,allow_other,blksize=4096,default_permissions)
/dev/sr0         /live/image              iso9660    (ro,noatime)

...(a bunch of config file info- let me know if anyone wants to see it!)

But usually I just get "Cannot Display This Video Mode", which I know means the video output is not usable by the monitor.

I'm looking for a way to get into a recovery mode.I'd really like to avoid wiping the drive.

Any thoughts?

  • Grub does not use PBR - partition boot sector to boot normally (you have to have another system with grub2 and chain load to it). So you are only booting from MBR. It seems more like you are booting, shift key as posted should work, but some have to use escape? What video card/chip do you have. Grub also remembers keys. Right after BIOS, if you press down arrow once you will be in second boot entry or recovery (not sure it works with new submenu, which may need two down presses).
    – oldfred
    Aug 2, 2013 at 4:46

2 Answers 2


Press Shift during boot, that should show you the grub menu.

  • Thank you, but I've tridd that several times and it does not work. Could a missing core.img cause the behavior I'm seeing?
    – Nick
    Sep 6, 2012 at 16:51
  • How about you boot from the CD in rescue mode and run update-grub?
    – January
    Sep 6, 2012 at 18:41

You can also try to install Grub Customizer and make changes to Grub as you need. However, proceed with caution. Grub Customzier is a comfortable GUI tool that allows you to make changes to the Grub menu, order of items, if and how it appears and much more.

To install:

sudo add-apt-repository ppa:danielrichter2007/grub-customizer
sudo apt-get update
sudo apt-get install grub-customizer

You can find more information about Grub Customizer in the following post:

How do I change the GRUB boot order?

Hope that helps!

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