title: Yet Another 'The project was not built since its build path is incomplete'
body: <p>I have an Android project that I've been happily building for weeks in Eclipse Indigo.  <strong>I have not changed any settings, libraries, or workspace components, or added or removed any files</strong>.    A few hours ago I was doing a "Run as" to run my app on a phone and Eclipse did a hard hang.   I couldn't even kill it in Task Manager so I rebooted my PC.</p>
  
  <p>Now when I try to build my app I get 
  <em>"The project was not built since its build path is incomplete. Cannot find the class file for java.lang.Object. Fix the build path then try building this project"</em></p>
  
  <p>I deleted gen and did a clean and build with the same result.   In the project Properties for the build path, in the Libraries tab it shows </p>
  
  <ul>
  <li>Android Dependencies</li>
  <li>Android Private Libraries</li>
  <li>Unable to get system library for the project.</li>
  </ul>
  
  <p>Any idea what's going on?  This Eclipse "build path is incomplete" error is very common but when I search Stack Overflow and Google, most of the cases seem to be related to importing new projects, moving workspaces, changing libraries or other things I didn't do.</p>
  
  <p>Thanks in advance!</p>