Who own's the . of /media/disk? If it's not your user, and the disk is chmoded 755 or something, you won't be able to write. <BR><BR>Do your users all have the same UID on all of your machines?

So, I work with developers of varying skills. This one set is not so skilled; they have this "chmod 777 everything" rule in their code, which is stupid, but normally this hasn't affected anything ...