title: Android: Emulator frequently disconnected (offline)!
body: <p>Sometime just after I launched a new emulator, for very first time I was trying to upload my apk, however I got "emulator: ERROR: the user data image is used by another emulator. aborting".</p>
  
  <p>I launched a new emulator, and left it alone, several minutes later, DDMS showed "device offline".</p>
  
  <p>I had to restart a new one, you know, minutes wasted.<br>
  It's really bothering that I keep getting this error and slowed down debugging.<br>
  How do I fix it?</p>