When going to nether or overworld from the other the loading fails no matter how long I wait. Then when I log back in it immediately kills me, my items dissappear, this has happened to me three times each time I lose everything!!!!

When going to nether or overworld from the other the loading fails no matter how long I wait.  Then when I log back in it immediately kills me, my items dissappear, this has happened to me three times each time I lose everything!!!!