can't remove partitions in Vinux

[Lenny]

Hi,
I messed my install of Vinux, so I booted up to a live copy, of the same 
version, 4.0, and in the terminal, I have tried unmounting some partitions 
from the messed Vinux and although they say unmounted when I run:
sudo umount /dev/sda5
and
sudo umount /dev/sda2
these partitions won't be deleted.
I tried both in gparted and parted.
those programs tell me that the partitions are mounted, but umount tells me 
that they are not.
I rebooted, hoping that an updated fstab would fix things, but the same 
thing.
I removed /dev/sda1 first, that one went okay.
Any ideas?
Thanks.

Glenn