title: Android Studio suddenly cannot resolve symbols
body: <p>Android Studio 0.4.2 was working fine and today I opened it and almost everything was red and the auto-completion had stopped working. I look at the imports and AS seems to be telling me it can't find <strong>android.support.v4</strong> all of a sudden (offering me the option to remove the unused imports). (<strong>android.support.v7</strong> seems to be fine though).</p>
  
  <p>Things I have tried: </p>
  
  <ul>
  <li>Rebuilding the project</li>
  <li>Cleaning the project</li>
  <li>Syncing with Gradle Files</li>
  <li>Closing the Project, closing AS and relaunching / reopening</li>
  <li>File > Invalidate Caches / Restart</li>
  <li>Examining Lint, didn't see anything obvious</li>
  <li>Double checking all support libraries are up to date in the SDK manager</li>
  <li>Examining my Build.gradle, although no changes and it's the same as usual, the way it was working all the time.</li>
  </ul>
  
  <p>Here it is in case it's relevant:</p>
  
  <pre><code>buildscript {
      repositories {
          mavenCentral()
      }
      dependencies {
          classpath 'com.android.tools.build:gradle:0.7.+'
      }
  }
  apply plugin: 'android'
  
  repositories {
      mavenCentral()
  }
  
  android {
      compileSdkVersion 19
      buildToolsVersion '19.0.0'
  
      defaultConfig {
          minSdkVersion 8
          targetSdkVersion 19
      }
  }
  
  dependencies {
      compile 'com.android.support:support-v4:19.0.0'
      compile 'com.android.support:gridlayout-v7:19.0.0'
      compile 'com.android.support:appcompat-v7:19.0.0'
      compile 'com.google.android.gms:play-services:4.0.30'
      compile project(':libraries:facebook')
      compile files('libs/core.jar')
  }
  </code></pre>
  
  <p>When I hit "Sync with Gradle" and open "Project Settings" I get a red error telling me I have duplicate library references and to remove the unused ones.. 
  <img src="https://i.stack.imgur.com/YACON.jpg" alt="enter image description here"></p>
  
  <p>My project compiles and runs fine but I really need the autocomplete working!! Does anyone have any suggestions?</p>
  
  <p><img src="https://i.stack.imgur.com/ZzJDV.jpg" alt="enter image description here"></p>