Hello. I have a month old MBA and I've just noticed that whenever I close the laptop or put it to sleep in any other way - the moment I wake it up I see a red error message: "The disk was not ejected properly. If possible, always eject a disk before unplugging it or turning it off". After that I can no longer find neither my USB 3.0 WD External HDD nor my 32GB SD card in the device list. Any help?