Comment 6 for bug 45989

I also encountered this bug, so maybe I can help. I was actually using Linux Mint 3.0, but since it's based on Ubuntu 7.04, I believe it's a Ubuntu bug.

Ok, here it is:
I have 2 IDE harddisks, a primary master (hda) with Windows XP and a primary slave (hdb) with PCLinuxOS 2007. On hda's MBR I had the XP boot loader, while on hdb's MBR I had PCLOS's grub.
Also, I had changed my BIOS to boot from hdb, so I would get the grub menu.

When I installed Mint, the boot configuration was messed up - the new grub from Mint wouldn't boot anything. When trying to boot, I got the following grub errors (I believe the grub stage is 1.5):
 * for Mint - grub error 17: Cannot mount selected partition
 * for WinXP - grub error 13: Invalid or unsupported executable format
 * for PCLOS - grub error 22: No such partition

 After some fiddling with grub, I decided to use PCLOS's grub => I simply copied the entries from Linux Mint's menu.lst to PCLOS's menu.lst and restored grub from PCLOS. Now PCLOS and WinXP worked, but Mint still gave error 17.
So I looked in the menu.lst and devices.map => I discovered something:
hd0 and hd1 wre swapped. In other words, hd0 was referruing to hdb, and hd1 to hda.
But the Mint entries were using hd1 => they were looking on the wrong disk.

I'm not sure, but I think that when my BIOS boots from hdb, it automatically swaps hda and hdb => hdb will be the first disk (hd0) and hda will be the second disk (hd1).
Apparently, the PCLOS installer correctly detected this and wrote the menu.lst accordingly.

I'm not sure if this helps, but I sure hope it does (this is one nasty bug IMHO).
If you need more details, please contact me.