Cant moves files from my My Book to another hard drive

hi there, recently i have put my library of 180 gig of movies onto my My Book and now im wanting to move them back onto the hard drive and the My Book wont let me. I cant move the files anywhere except the desktop. Also FYI when i put my other WD hard drive in it has an icon of the hard drive but on the left it has a cirle with an arrow pointing to red on the right. Does this have anything to do with the problem



Are you getting any error messages? Can you post a screenshot of the error?