You might want to read the message a little closer.. ;-) it says Logic can't WRITE to the file so it can't create a wave image and you won't be able to save it with destructive editing (optimizations etc). Logic can read the file but does not have permission to write to it.
My guess is, you've dragged an AIF file straight from a CD into the arrange window? You might want to copy it to the harddisk first and drag it in from there. If you already did that and still get this message, you can right-click on the aif file and enable write permission for it.