Problem Activating "Windows Communication Foundation Non-HTTP Activation" feature in Windows 7

I'm having the following problem. I'm installing SharePoint 2010 Beta so I need to activate the windows feature "Windows Communication Foundation Non-HTTP Activation". The problem is I cannot activate it, i get the message: "An error has occurred. Not all features were successfully changed"

When i look at the log (C:\Windows\Logs\CBS\CBS.log) I found this error:

Process output: [l:186 [186]"SMConfigInstaller[Error]: Failed in calling 'StartService' for service 'NetTcpActivator'. Error code: 0x8007042c

Anyone can give me a clue of what is happening here?

OK, I finally solved it. I uninstalled .NET Framework 4.0 and then the feature activated correctly, and then I installed .NET Framework 4.0 again.