Fedora Installation :: Dual Boot: FC13 - Est4 - Ubuntu10.04 - Ext3 ?

I'm running Ubuntu Lucid formatted ext3. It boots with Grub (old Grub) in sdb6 (hd1,5) It mounts at /, and its partition, sdb6. is flagged boot.

I created a new partition for Fedora 13, 64bit. I installed Fedora in sdb8 (hd1,7), formatted ext4, and created a separate /home in sdb7, formatted ext3, so I might share it with Ubuntu, in sdb6.

Fedora installed with Grub2. It booted fine, and after adjusting references in fstab Ubuntu booted OK too, but rather roughly.

That is when I shifted the boot flag to the Ubuntu partition. So now the original Ubuntu Grub is handling boot once again. Ubuntu boots as before, but I can't get Ubuntu's Grub to boot Fedora. An earlier post suggested this code, which generated error 13, Invalid or inappropriate executable:

Code:

I tried the following code, pasted from the Fedora Grub, but it doesn't work either:

Code:

I've got alternative lines invoking the kernel, because someone had suggested omitting the direct reference to root= ....

Either way I get error 2 - Bad File or directory.

I suspect the problem may be that I'm booting Grub in an ext3 partition and trying to invoke Fedora in an ext4 partition. Does anyone know if that is the likely cause of my problem? If so I can reinstall Fedora formatted ext3.

Alternatively, can I create a Fedora /boot partition, and move/reinstall Grub there? Either way -- should I use old Grub, so both Grubs are the same?

Should I have assigned mount points to sdb8 (Fedora) and sdb7 (home)? Currently I'm not using sdb7 at all.

I'll attach a screenshot from GParted of my partitions.