First, to change the read-only property of a file, right click it, and chose properties. At the bottom is a check-box for "Read-only". Try to un-check it.
As a second step, I need to know where you are are putting the MDB file (which folder). If the folder is a read-only file, then sometimes the file placed there will inherit that and also become read-only, also if you manually un-check file itself; Try to put the MDB-file in your Personal Folders or some place where you know you have read-and-write rights and see if it works.
BTW, what version of Access do you have? And what version Windows?
Going through 'properties' worked...sort of, the external file LDDManager.mdb. is not read-only anymore, but the files inside still think they are. I did move the files to my personal ones. I have Access Runtime 2003, and Windows 7. Why does my computer hate me? haha