title: sometimes my file just freezes in my vi |vim, what happened?
body: <p>Sometimes when I edit my file using vi or vim, my file just freezes. Even if I type <kbd>Ctrl+C</kbd> or <kbd>Ctrl+D</kbd>, it still freezes there. I <code>kill -9 &lt;pid&gt;</code> from another terminal, the pid is killed, but the file still freezes there.   </p>
  
  <p>I guess I must have typed some combination of key which I do not know. Does anybody have an idea?</p>