Visual Studio 2010 (Beta 1) and Ribbon Control

If you downloaded the RibbonControlsLibrary.dll  and having a hard time, for example I was having this error:

Undefined CLR namespace. The ‘clr-namespace’ URI refers to a namespace ‘Microsoft.Windows.Controls.Ribbon’ that is not included in the assembly.

you should read the comments found at the bottom of this post:

http://teusje.wordpress.com/2009/08/12/wpf-office-ribbon-control/

basically the dll is being blocked by the OS and visual studio is unable to load and use it, the solution is right click on the file and unblock it; after that  you may need to recreate(add\delete) the reference or\and open/close the solution again.