SCCM 2012 R2 OSD Waiting to Install; package is blank

Hello,

I just upgrade my SCCM site to R2. Now when I run a OSD for windows 7, the task sequence stops after installing the configuration manager client, and client update. 

If I then go to Software Center and try to install a package, the package gets stuck at "Waiting to install" after it finishes downloading. 

The execmgr.log shows:

Package DEN0000D, program setup.exe is ready but can not be started because package , program  is currently running.

I checked that:

1. config manager client is up to date.
2. all content is current on DP

thanks for you help!