My time machine drive has been full for some time and it deletes old copies to make room for new ones- fine with me. 2 days ago though it said there was an error. Now it won't back up and somehow the drive was changed to "read only". This is my private PC and 250 gig external drive (the time machine drive). It has never been protected or read only. Unfortunately I don't know how to change it back to "read and write". I did notice that it says I can still read and write in one area, but then it also says "you can only read" but perhaps the drive is treating me like "everyone", where it says "read only" and it should be treating me like "me". Any help welcome !!