title: Warning - Build path specifies execution environment J2SE-1.4
body: <p>I create a Maven project in Eclipse Helios. It works fine for a day, but then this warning shows up:</p>
  
  <blockquote>
    <p>Build path specifies execution environment J2SE-1.4. There are no JREs installed in the workspace that are strictly compatible with this environment. </p>
  </blockquote>
  
  <p>Since this message, the project stopped compiling and debugging. Does anyone have solution for this problem?</p>