Inserting a 2GB thumb drive on my 8.04 (your Feisty Fawn is 7.04), I
get the identical display with Properties, but one thing you omitted
is what's at the top of the Properties box: "Owner". On mine it displays
"Owner: thad - Thad Floryan".

What does yours display?

This is a stretch, but what kind of filesystem is on your USB devices?
The thumb drive I just tested is "FAT" (not "FAT32" or "NTFS" or any
Linux filesystem).

I'm able to copy files to the USB thumb drive using either the command
line or copy'n'paste.

A "df" shows the USB thumb drive as "/dev/sdb1" automounted on
"/media/THUMB_2GB" (I relabelled all my thumb drives after removing
the "U3 Smart" junk).

A quick workaround may be to simply burn a CD or DVD with your data.

My USB is MS-DOS (FAT32) with Sharing & Permissions "You can read and write."
There would appear to be no other information of any interest.
The "Owner" is given as "dellc400 - Dell C400". (Yes, it's a museum piece. I got
it on eBay and the vendor doesn't seem to be in business any more.)
The device used to allow me to copy onto a thumb drive. Curiouser and curiouser.
I'm going to go to work and see if I can get an internet connection there and
mail my files to myself.
But I'd really like to be able to reliably use USB drives on it...
A search under "The Permissions Cannot Be Changed" has not enlightened me. Here
is an example:
ubuntuforums.org/archive/index.php/t-278899.html



Please visit our website at
http://www.geocities.com/evan_j_siegel

Is that your (as in "you") login username, "dellc400", as shown
in Properties' window?

If not, that might be the problem -- not being the owner.

I have no idea how, during my quick test, it picked up my username
as the owner unless the system assigns ownership to whomever is
logged in when a USB device is plugged in.

From a command line, a "ls -l mountpoint" would reveal exactly the
nature of the problem regarding {owner, group, other} permissions.
The "mountpoint" would be /media/whatever with "whatever" being
that which is shown by a "df" command.

> [...]
> A search under "The Permissions Cannot Be Changed" has not
> enlightened me. Here is an example:
> ubuntuforums.org/archive/index.php/t-278899.html

I agree. Again, the "ls -l" will show what's causing the problem
(unless, in fact, the drive is write protected as another respondent
mentioned; half my thumb drives have write-protect tabs and the others
do not).

Interesting. I just now ran another test plugging-in the same USB
thumb drive before I logged in; I wanted to see who the system
would assign as "owner" of the thumb drive.

Now Properties cannot show anything about the thumb drive, though
I can, after logging in, copy and delete files on the thumb drive.

Clearly, the system is confused, and this is with the latest patches
for 8.04 as of yesterday (Saturday).

Unmounting the thumb drive works OK either from the command line or
the graphical interface.