Alex
Esse erro tem a ver com o debugger do Visual Studio.
Dê uma olhada no post no nosso colega americano, Swami Ayyappa, que teve o mesmo problema:
http://forums.microsoft.com/MSDN/ShowPost.aspx?PostID=137287&SiteID=1
"Hi,
When I tried to debug the Sample application with RTM, it gives the following error.
Unable to attach. The binding handle is invalid
To resolve this error I made changes in Administrative Tools >> Services >> Terminal Services.
I had changed the properties of this service that is I had changed Startup Type as Manual and started the service and after that restarted my system.
Now Debugging is working perfectly.
Hope this helps"