I get this same error.  I'm running 64-bit Ubuntu 8.10.  I open Partition Editor from the menu and look at /dev/sda.  The first item listed there is /dev/sda3.  It's a 214GB NTFS primary partition.  There's a yellow warning triangle next to it, and its Windows label (CURRENT) isn't shown.  When I double-click on it, or when I right-click on it and choose Information, I get an indication that it is not mounted and a statement, "Unable to read the contents of this filesystem!"  It is a working partition that I was just using in WinXP before rebooting into Intrepid on this dual-boot AMD system.  I did a normal shutdown and reboot when leaving WinXP; no system reset or anything like that.

In Nautilus, when I click Computer and then double-clicke on CURRENT, I get this:

  Cannot mount volume.
  You are not privileged to mount the volume 'CURRENT'.

After a few seconds, I get a dialog that says this:

  Opening "CURRENT".
  You can stop this operation by clicking cancel.

A few seconds later, I get this dialog on a different desktop:

  Unable to mount location
  DBus error org.freedesktop.DBus.Error.NoReply: Did not receive a reply. Possible causes include: the remote application did not send a reply, the message bus security policy blocked the reply, the reply timeout expired, or the network connection was broken.

Double-clicking opens the other NTFS partitions on this system without difficulty.

I can't get at this partition with these steps:

  sudo -i
  nautilus
  [browse to /media]

That doesn't work because CURRENT is not shown as one of the partitions there, and when I click on Computer at that location, I get this error:

  Could not display "computer:".
  Nautilus cannot handle "computer" locations.

I have added a line to my /etc/fstab that attempts to mount the partition, but it's not working.  The fstab is:

**************************************************

# /etc/fstab: static file system information.
#
#  -- This file has been automaticly generated by ntfs-config -- 
#
# <file system> <mount point>   <type>  <options>       <dump>  <pass>

proc /proc proc defaults 0 0
# Entry for /dev/sdb5 :
UUID=997ccdbf-265c-4024-a314-b78b71f2d122 / ext3 relatime,errors=remount-ro 0 1
# Entry for /dev/ !! UNKNOW DEVICE !! :
UUID=903fa40e-f48a-45b2-a6b4-8fb5b24f74df none swap sw 0 0
/dev/scd0 /media/cdrom0 udf,iso9660 user,noauto,exec,utf8 0 0
/dev/sdc8 /media/CURRBACKUP ntfs-3g defaults,locale=en_US.UTF-8 0 0
/dev/sdc7 /media/COLDSTORAGE ntfs-3g defaults,locale=en_US.UTF-8 0 0
/dev/sda5 /media/BACKROOM ntfs-3g defaults,locale=en_US.UTF-8 0 0
/dev/sda3 /media/CURRENT ntfs-3g defaults,locale=en_US.UTF-8 0 0

**************************************************

Not sure what that "UNKNOW DEVICE" line is all about.

df -k gives me this:

Filesystem           1K-blocks      Used Available Use% Mounted on
/dev/sdb5             30232016   5225188  23778180  19% /
tmpfs                  2543908         0   2543908   0% /lib/init/rw
varrun                 2543908       132   2543776   1% /var/run
varlock                2543908         0   2543908   0% /var/lock
udev                   2543908      2836   2541072   1% /dev
tmpfs                  2543908       232   2543676   1% /dev/shm
lrm                    2543908      2380   2541528   1% /lib/modules/2.6.27-7-generic/volatile
/dev/sdc8            244983184     73536 244909648   1% /media/CURRBACKUP
/dev/sdc7            262140604    144156 261996448   1% /media/COLDSTORAGE
/dev/sda5            157284312  72347492  84936820  46% /media/BACKROOM

Thanks for guidance/insights/fixes.

Cheers!

Ray