root filesystem not displayed anywhere

I cannot see anywhere how much space is free or used on my "/" filesystem. I'm using Feisty, bug Edgy had the same problem. I do not know exactly when it stopped showing up but it might been after upgrade from Dapper to Edgy.

Specifically, I can check the free/used space of my other partitions (/home, several others with ext3 and fat32) but not the root here:
- Gnome System Monitor - "File Systems" tab
- 'df' and 'sudo df' in terminal
- It's also not displayed on 'mount' in terminal

I DO see the partition with gparted, the correct space is also displayed there. But when I right-click it there and choose "Information", every partition (not just the root partition) shows me "Not Mounted" in the Status field. This is probably unrelated to this bug.

The output of 'sudo df':
Filesystem 1K-blocks Used Available Use% Mounted on
varrun 517892 120 517772 1% /var/run
varlock 517892 4 517888 1% /var/lock
procbususb 517892 216 517676 1% /proc/bus/usb
udev 517892 216 517676 1% /dev
devshm 517892 0 517892 0% /dev/shm
lrm 517892 33788 484104 7% /lib/modules/2.6.20-15-generic/volatile
/dev/mapper/sda8 33641448 26239428 5693108 83% /home
/dev/mapper/sda6 91499936 76539484 10312448 89% /media/storage1
/dev/mapper/sdb1 240362656 223719180 4433676 99% /media/storage2
/dev/mapper/hda5 72548608 51276416 21272192 71% /media/storage3
/dev/mapper/hdb5 76920384 43682904 29330076 60% /media/storage4

my /etc/fstab:
# /etc/fstab: static file system information.
#
# <file system> <mount point> <type> <options> <dump> <pass>
proc /proc proc defaults 0 0
# /dev/sda7 -- converted during upgrade to edgy
UUID=9CF2-9C80 / ext3 defaults,errors=remount-ro 0 1
# /dev/sda8 -- converted during upgrade to edgy
UUID=3bf61968-d8f2-4a5b-a70f-1c44c542a871 /home ext3 defaults 0 2
# /dev/sda6 -- converted during upgrade to edgy
UUID=e11ea37e-d1a6-4f62-89dc-a883dac7eb9d /media/storage1 ext3 defaults 0 2
# /dev/sdb1 -- converted during upgrade to edgy
UUID=7e68c5b7-7443-4c44-a32a-14cb40705c21 /media/storage2 ext3 defaults 0 2
# /dev/hda5 -- converted during upgrade to edgy
UUID=9CE0-67EA /media/storage3 vfat defaults,utf8,umask=000,gid=0 0 1
# /dev/hdb5 -- converted during upgrade to edgy
UUID=b5cd00fa-307e-4339-b73c-e5e4d41823fc /media/storage4 ext3 ro 0 2
# /dev/hda7 -- converted during upgrade to edgy
UUID=59c158c3-4757-4ddb-8dac-30f2203c93f1 none swap sw 0 0
/dev/hdc /media/cdrom0 udf,iso9660 user,noauto 0 0
/dev/cdrom /media/cdrom1 udf,iso9660 user,noauto 0 0
/dev/fd0 /media/floppy0 auto rw,user,noauto 0 0

output of 'sudo mount':
proc on /proc type proc (rw,noexec,nosuid,nodev)
/sys on /sys type sysfs (rw,noexec,nosuid,nodev)
varrun on /var/run type tmpfs (rw,noexec,nosuid,nodev,mode=0755)
varlock on /var/lock type tmpfs (rw,noexec,nosuid,nodev,mode=1777)
procbususb on /proc/bus/usb type usbfs (rw)
udev on /dev type tmpfs (rw,mode=0755)
devshm on /dev/shm type tmpfs (rw)
devpts on /dev/pts type devpts (rw,gid=5,mode=620)
lrm on /lib/modules/2.6.20-15-generic/volatile type tmpfs (rw)
/dev/mapper/sda8 on /home type ext3 (rw)
/dev/mapper/sda6 on /media/storage1 type ext3 (rw)
/dev/mapper/sdb1 on /media/storage2 type ext3 (rw)
/dev/mapper/hda5 on /media/storage3 type vfat (rw,utf8,umask=000,gid=0)
/dev/mapper/hdb5 on /media/storage4 type ext3 (ro)
binfmt_misc on /proc/sys/fs/binfmt_misc type binfmt_misc (rw)