The media is write protected.

when trying to transfer a file from laptop to desktop external drive. i get the message that the media is write protected, this seems odd as i write to it quite often,
when i access the laptop via the homegroup and copy and paste to the external, it copies fine ,so i am perplexed as to how to remove the write protection ,ive had a look in security in the properties on the external but they look fine and all the permissions seem to be set correctly. any ideas.
its a real pain as the most space is on the external and i want to empty up the laptop

ha ,sorry i thought i had mentioned it, im using a data link cable.

no the laptop to pc using file transfer cable via the cable's software to the external that is constantly plugged into the desktop.

ok the files are on the laptop, the external is plugged into the desktop.
using a data transfer cable from lappy to the desktop with the target folder on the external. which tells me its write protected when i try to move a folder to it,
as a workaround i am moving folders from lappy to my user folder on the desktop ,then i will move them to the ezternal, its just that its a pain transfering the data twice instead of it going to the external in the first place.
i suppose an easier way would be to plug the external into the lappy and move them that way. its just that the way my set up is i dont wanrt to mess about moving drives etc.

Have you tried to take ownership?

one of these.
Windows 7 Vista XP USB 2.0 Data Link Transfer Cable: Amazon.co.uk: Electronics

and the driver software that came with it. it allows the computers to see each other, and drag and drop the files for transferring