Cannot build after move to Qt5.2.1

[user001]

Just installed the latest release with Qt Creator 3.0.1 on Windows via the binary executable. The working existing project (Qt5.0.2) cannot compile any more. Some errors are listed here:

• error: C1083: Cannot open include file: 'QtWidgets': No such file or directory
  error: C2248: 'QThread::sleep' : cannot access protected member declared in class 'QThread'*

I thought it should be no changes between Qt5s.
After I uninstalled the Qt5.0.2 and installed the Qt5.2.1. I launched the project from the File -> Recent Project. And then did the configuration (didn't change anything actually), Run qmake and then Build project.

How to fix these errors?

[sierdzio]

Remove .pro.user file from your project, remove the Makefile and your build directory. Then open the project in Qt Creator, run qmake and rebuild.