"Could not load file or assembly..." DotNetOpenAuth + MVC3

I'm getting the following error

    Could not load file or assembly 'file:///C:\Users\<project path>\bin\DotNetOpenAuth.dll'
    or one of it's dependencies. Operation is not supported. 
    (Exception from HRESULT: 0x80131515)

I get this when I try to add a Controller to my Controllers folder within the MVC3 framework.

I've only recently started using MVC3 and DotNetOpenAuth, I've been using a tutorial to try to learn it, the part I am replicating is this: http://www.asp.net/mvc/tutorials/getting-started-with-aspnet-mvc3/cs/adding-a-model

I can still run the project and everything works fine, I simply cannot add Controllers.

I'm using VS .NET 2010 (64 bit) on Windows 7.

Let me know if there's any additional information that is needed, thank you in advance!

It may be related to this: http://blogs.msdn.com/b/brada/archive/2009/12/11/visual-studio-project-sample-loading-error-assembly-could-not-be-loaded-and-will-be-ignored-could-not-load-file-or-assembly-or-one-of-its-dependencies-operation-is-not-supported-exception-from-hresult-0x80131515.aspx

Which says you need to unblock the assembly within windows explorer.