You'll have to mount in the command line as Root.
# mount -t <file system type: vfat, ntfs, etc.> /dev/<sd* or hd*> /mnt
You'll need to specify the file type if it's anything other than a standard GNU/Linux type. You'll also need to specify which partition of the drive you want to mount sda*, sdb*, hda*, hdb*. SCSI devices: sda - master, sdb - slave. IDE devices: hda - master, hdb - slave.