now i am trying another example and something weird is going on here

this is my example in main.cpp
Qt Code: 
  1. #include <QtGui>
  2.  
  3.  int main(int argc, char *argv[])
  4.  {
  5.      QApplication app(argc, argv);
  6.      QWidget window;
  7.      window.resize(320, 240);
  8.      window.show();
  9.      window.setWindowTitle(
  10.          QApplication::translate("toplevel", "Top-level widget"));
  11.      return app.exec();
  12.  }
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above code worked fine on first couple of run
but when i change
Qt Code: 
  1. window.resize(320,240);
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to
Qt Code: 
  1. window.resize(20,240);
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it didnt work and displayed error which is this in compile output tab
Qt Code: 
  1. Running build steps for project creatingWindow...
  2. Configuration unchanged, skipping qmake step.
  3. Starting: "C:/Qt/2010.04/mingw/bin/mingw32-make.exe" -w 
  4. mingw32-make: Entering directory `C:/Qt/2010.04/examples/creatingWindow-build-desktop' 
  5. C:/Qt/2010.04/mingw/bin/mingw32-make -f Makefile.Debug 
  6. mingw32-make[1]: Entering directory `C:/Qt/2010.04/examples/creatingWindow-build-desktop' 
  7. g++ -c -g -frtti -fexceptions -mthreads -Wall -DUNICODE -DQT_LARGEFILE_SUPPORT -DQT_DLL -DQT_GUI_LIB -DQT_CORE_LIB -DQT_THREAD_SUPPORT -DQT_NEEDS_QMAIN -I"..\..\qt\include\QtCore" -I"..\..\qt\include\QtGui" -I"..\..\qt\include" -I"..\..\qt\include\ActiveQt" -I"debug" -I"." -I"..\creatingWindow" -I"." -I"..\..\qt\mkspecs\win32-g++" -o debug\main.o ..\creatingWindow\main.cpp 
  8. g++ -enable-stdcall-fixup -Wl,-enable-auto-import -Wl,-enable-runtime-pseudo-reloc -mthreads -Wl -Wl,-subsystem,windows -o debug\creatingWindow.exe debug/main.o debug/mainwindow.o debug/moc_mainwindow.o -L"c:\Qt\2010.04\qt\lib" -lmingw32 -lqtmaind -lQtGuid4 -lQtCored4 
  9. mingw32-make[1]: Leaving directory `C:/Qt/2010.04/examples/creatingWindow-build-desktop' 
  10. mingw32-make: Leaving directory `C:/Qt/2010.04/examples/creatingWindow-build-desktop' 
  11. mingw32-make[1]: *** [debug\creatingWindow.exe] Error 1 
  12. mingw32-make: *** [debug] Error 2 
  13. The process "C:/Qt/2010.04/mingw/bin/mingw32-make.exe" exited with code %2.
  14. Error while building project creatingWindow (target: Desktop)
  15. When executing build step 'Make'
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and when i change it back to original example code then again it display this error. on the first two executions it worked but then it fails.

help please?