Could it be mounted as another user? I'm assuming it is an external hard drive. I have a really small (in size) firelight external drive myself.
Do you want to read or read and write to the drive?
Enter "mount" in the terminal. Is this device listed?
If so, what filesystem is used, ntfs or ntfs-3g? I wouldn't try writing with ntfs. The ntfs-3g filesystem uses the "fuse" kernel module and operates in userspace. This makes development easier and it seams to be further along in development and easier to use. You may need to install a "fuse" package and an "ntfs-3g" package if they aren't installed.
If you enter "lsmod" and the "fuse" kernel module is listed, then it is installed. If it isn't listed but "sudo /sbin/modprobe fuse" works, then it is installed but just needed to be loaded.
Here is how my Windows partition is mounted: (the fstab entry)
/dev/sda1 /mnt/xp ntfs-3g rw,nosuid,nodev,uid=jschiwal,fmask=0177,dmask=0077,utf8 0 0
You would use your own username. For an external drive, also use the "noauto" option. Also use either "UUID=" or "LABEL="
instead of a device node in the first field. The next time you connect an external device it might be using a different device node.
udevinfo -q env -n /dev/sda1
The udevinfo command can be run as a normal user and supplies a lot of information on hardware devices. You could also look in /dev/ for the info (/dev/disk/by-label or /dev/disk/by-uuid):
ls /dev/disk/by-label/ -l
lrwxrwxrwx 1 root root 10 Feb 17 04:14 My\x20Book -> ../../sdd1
This assumes that your system uses HAL which I think it does.