Hello everybody, I installed Centos 6.2 on a computer with an older version of it in order to dual boot both of them. I managed to install the new OS on a physically seperated hard drive, and configured grub to make the newly installed OS the default one. Now the older OS won't boot and this error message shows: *"error 13: invalid or unsupported executable format"*. I attached to the email the output of *"fdisk -l"* and a copy of the *"/etc/grub.conf"* configuration file. I have no experience dealing with boot/grub issues, so any help on this will be much appreciated. Regards. -------------- next part -------------- [root at mypc ~]# fdisk -l Disk /dev/sda: 80.0 GB, 80000000000 bytes 255 heads, 63 sectors/track, 9726 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00000080 Device Boot Start End Blocks Id System /dev/sda1 * 1 9472 76077056 83 Linux /dev/sda2 9472 9726 2045952 82 Linux swap / Solaris Disk /dev/sdb: 80.0 GB, 80032038912 bytes 255 heads, 63 sectors/track, 9730 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0xdbdbdbdb Device Boot Start End Blocks Id System /dev/sdb1 * 1 13 104391 83 Linux /dev/sdb2 14 9730 78051802+ 8e Linux LVM Disk /dev/mapper/VolGroup00-LogVol01: 2080 MB, 2080374784 bytes 255 heads, 63 sectors/track, 252 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x30307800 Disk /dev/mapper/VolGroup00-LogVol01 doesn't contain a valid partition table Disk /dev/mapper/VolGroup00-LogVol00: 77.8 GB, 77812727808 bytes 255 heads, 63 sectors/track, 9460 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00000000 Disk /dev/mapper/VolGroup00-LogVol00 doesn't contain a valid partition table [root at mypc ~]# -------------- next part -------------- # grub.conf generated by anaconda # # Note that you do not have to rerun grub after making changes to this file # NOTICE: You do not have a /boot partition. This means that # all kernel and initrd paths are relative to /, eg. # root (hd1,0) # kernel /boot/vmlinuz-version ro root=/dev/sda1 # initrd /boot/initrd-[generic-]version.img #boot=/dev/sdb default=0 timeout=5 splashimage=(hd1,0)/boot/grub/splash.xpm.gz hiddenmenu title CentOS (2.6.32-220.17.1.el6.i686) root (hd1,0) kernel /boot/vmlinuz-2.6.32-220.17.1.el6.i686 ro root=UUID=b5d4d678-1e3d-47ce-acf1-d061097b6885 rd_NO_LUKS KEYBOARDTYPE=pc KEYTABLE=fr LANG=en_US.UTF-8 rd_NO_MD quiet SYSFONT=latarcyrheb-sun16 rhgb crashkernel=auto rd_LVM_LV=VolGroup00/LogVol01 rd_NO_DM initrd /boot/initramfs-2.6.32-220.17.1.el6.i686.img title CentOS IPBX (2.6.32-220.el6.i686) root (hd1,0) kernel /boot/vmlinuz-2.6.32-220.el6.i686 ro root=UUID=b5d4d678-1e3d-47ce-acf1-d061097b6885 rd_NO_LUKS KEYBOARDTYPE=pc KEYTABLE=fr LANG=en_US.UTF-8 rd_NO_MD quiet SYSFONT=latarcyrheb-sun16 rhgb crashkernel=auto rd_LVM_LV=VolGroup00/LogVol01 rd_NO_DM initrd /boot/initramfs-2.6.32-220.el6.i686.img title VoisGate rootnoverify (hd0,0) chainloader +1