flikrview freezes during running and webkit example cannot run afterwards

err output:
Starting C:\qt\Qt5.0.0-rc1\5.0.0-rc1\Src\qtwebkit-examples-and-demos\examples\qml\flickrview\debug\flickrview.exe...
QML debugging is enabled. Only use this in a safe environment.
Failed to start " QtWebProcess 428"
UIProcess\Launcher\qt\ProcessLauncherQt.cpp(187) : WebKit::ProcessLauncher::launchProcess
Remove me: fixing toplevel window flags
QOpenGLShader::link: "(37,18): warning X3206: implicit truncation of vector type

"
QOpenGLShader::link: "(35,18): warning X3206: implicit truncation of vector type

"
SHOULD NEVER BE REACHED

1 628EA402
2 6284B651
3 628E9CC4
4 627517A4
5 628EADF0
6 628EACE5
7 774094D2
8 773F43E9
9 767833AA
10 773D9EF2
11 773D9EC5
The program has unexpectedly finished.

after closing this app and try to run it again got the following output and the app doesn't run. Rebooting the system helps. (logging off doesn't help)

Starting C:\qt\Qt5.0.0-rc1\5.0.0-rc1\Src\qtwebkit-examples-and-demos\examples\qml\flickrview\debug\flickrview.exe...
QML debugging is enabled. Only use this in a safe environment.
Failed to start " QtWebProcess 420"
UIProcess\Launcher\qt\ProcessLauncherQt.cpp(187) : WebKit::ProcessLauncher::launchProcess
The program has unexpectedly finished.