Could not find file 'Microsoft.Windows.CommonLanguageRuntime, Version=2.0.50727.0

I have two windows application projects in the same solution, The solution contains an application that has a reference to another application in the same solution,

When I tried to publish the project that contains the reference it gave me that error :

Error 8 :Could not find file 'Microsoft.Windows.CommonLanguageRuntime, Version=2.0.50727.0

And another question:
If I will use the project 1 with all my project is it correct to make it Windows application and add reference to all other projects, or is there better way?

See these:
http://support.microsoft.com/kb/907757
http://social.msdn.microsoft.com/For...6-d7e20bd97674