77:  Why does the cursor always go to the wrong column when I move up or
 down one line?
  
  You have inadvertently typed "C-x C-n" (set-goal-column) which sets the
  "goal column" to the column where the cursor was.  To undo this type
  "C-u C-x C-n".
  
  If you make this mistake frequently, you might want to unbind or disable
  this command by doing one of these two:
  
    (define-key ctl-x-map "\C-n" nil)
    (put 'set-goal-column 'disabled t)