The Box just
re-appears with advice that the USB stick can not be removed
because one or more files are open.

I then opened a couple of the files and closed them. When I right
clicked and tried the 'Safely Remove' step again, this message appeared
in the bottom of screen panel;

'org.freedesktop.Hal.Device.Volume.NotMountedbyHal; Device to
unmount is not in/media/.hal-mtab so it is not mounted by HAL'

Taking this a step further, this machine does not even recognise
the plug-in of an Adata external drive.