can't mount FC3 in FC4!

[rayyes]

after installing FC4, i edited its menu.lst to include WinXP and FC3 which were already installed.

title Fedora Core 4 (2.6.11-1.1369_FC4)
root (hd0,6)
kernel /vmlinuz-2.6.11-1.1369_FC4 ro root=LABEL=/ rhgb quiet
initrd /initrd-2.6.11-1.1369_FC4.img
title Windows Xp
rootnoverify (hd0,0)
chainloader +1
title Fedora Core 3
root (hd1,0)
kernel /vmlinuz-2.6.9-1.667 ro root=/dev/VolGroup00/LogVol00 rhgb quiet
initrd /initrd-2.6.9-1.667.img

windows is hda1 hda5 and hda6
Fc3 is hdb1 (boot) and hdb2 (/)
Fc4 is hda7(boot), 8(/) and 9(/home).

when i boot into FC4, i can mount every partition on my box except for the / partition for FC3 (hdb2).

when i try it, i get:
$ sudo mount -t ext2 /dev/hdb2 /mnt/oldlinux
mount: /dev/hdb2 already mounted or /mnt/oldlinux busy

unfortunately, neither hdb2 is mounted, nor is /mnt/oldlinux busy! all other partitions mount fine. except for this one.
This happened from the moment i started using FC4, so its not like i changed any settings or anything.

Also, I CAN boot fine into FC3 from the grub menu, it works perfectly fine. except whne im in FC4 i can't mount it..
is there some blatantly obvious thing im missing here?

[rayyes]

DOH!! how stupid of me.
i was re reading my post and noticed the root=/dev/VolGroup00/LogVol00 next to the FC3 entry. I tried mounting that, and sure enough it worked.
nevermind..