I was having trouble trying to setup triple boot on my computer... (Take a look at this thread if you think it would help).
I ended up by having a GRUB menu that has Ubuntu entries and "Windows" entry, that calls an EasyBCD menu to choose between Windows 7 and XP.
Everything would be fine if, only if, GRUB was set up correctly.
I can't find why, but it throws me this when I try to open Ubuntu:
I've already tried to remove the menu.lst and do a grub-update, and a grub-install too.
I tried to create a symlink to /dev/sda1 at /dev/disk/by-uuid/<<uuid that is there>>, just like the other UUIDs that were there... But I couldn't find that symlink at that busybox that opened when it thrown me the error.
This is the GRUB entry with problems:
title Ubuntu 9.04, kernel 2.6.28-15-generic
kernel /boot/vmlinuz-2.6.28-15-generic root=UUID=b1ed36e5-4d84-4eb8-86ef-6f1135ffc238 ro quiet splash
And this my
04DCBCFBDCBCE856 -> ../../sdb1 (NTFS backup disk)
4434E77734E769FE -> ../../sda4 (NTFS WinXP)
ACB09F0DB09EDCE0 -> ../../sda2 (NTFS Win7)
b5311be8-a853-4fdd-aed5-d65974b3c0c4 -> ../../sda5 (EXT4 home)
C04B-4D97 -> ../../sdc (FAT32 live-pendrive from which i'm running)
D28447F68447DB9B -> ../../sda6 (NTFS files partition)
e0e88f38-d815-423a-9d5e-64b9c74a8b92 -> ../../sda7 (swap)