InternalInsonsistencyException in ios sdk4.3

Since I started using the IOS SDK4.3; not only have I experienced frequent crashes, I have also come across this very bad crash when I want to debug some apps: Error Log: "Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Could not load NIB in bundle: 'NSBundle (loaded)' with n开发者_JAVA技巧ame 'MainWindow''"

I have once escaped this horror by selecting a lower iPhone simulator version, but not all the time. What could actually cause this?

Probably, MainWindow.xib no longer exists in your project.