Fedora :: Gparted - Kernel Unable To Reread Partition Table On Disks

When I start gparted, to see if I can add extra harddisk where all my data is, I get the next error:

Code:
[root# gparted
libparted : 1.9.0

The kernel was unable to re-read the partition table on /dev/sda (Device or resource busy). This means Linux won't know anything about the modifications you made until you reboot. You should reboot your computer before doing anything with /dev/sda. I can start fedora 12 x64 amd whitout any problem. My partition layout on a single disk (80 gb sata maxtor) for the system is:
Code:
/
/home
swap

When I try to mount one of the extra disks (samsung spinpoint 1 tb, I have 4) I get to next error:
Code:
root# mount /dev/sdb1 /media/sdb1
mount: you must specify the filesystem type

If I add the option with the filesystem I get:
Code:
root# mount -t ext3 /dev/sdb1 /media/sdb1
mount: special device /dev/sdb1 does not exist

In gparted, when I select just a flag option, and deselect, press ok, the disk is forced to be reread by the program. After that I can also mount it. When I use any of the programs linked in this post, I am able to mount the disks whitout any problem. Except after a reboot, I get the same problem. SO whit each reboot, or poweroff, I need to do a re-read of the disks. The system is fedora 12 x64 for amd, installed from a live cd, the rest whit yums groupinstall, the latest kernel.