title: <Cocoa/Cocoa.h> is Missing
body: <p>I moved to Xcode 4.0 from Xcode 3.2.x<br>
  My existing project was compiling in Xcode 3.2 but when i moved to Xcode 4.0 its giving error in the file , </p>
  
  <p>ApplicationName_prefix.pch and saying </p>
  
  <p> file not found, </p>
  
  <p>I believe normally this file is suppose to be at </p>
  
  <p>System/Library/Frameworks/Cocoa.framework/Headers </p>
  
  <p>but in my machine this folder "Header" is Missing, </p>
  
  <p>does that mean, Xcode 4.0 was not installed correctly, </p>
  
  <p>PN : some projects compiling properly while some projects giving this kind of issue. </p>
  
  <p>If i need to reinstall, how can i do that </p>