I ran into a problem trying to authenticate with CRM 2011 Online, I received the following error message when I tried to run my code:

Could not load file or assembly ‘Microsoft.IdentityModel Version=3.5.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35’ or one of its dependencie. The system cannot fine the find specified.

The reason for receiving this error is because I don’t have the Windows Identify Foundation Pack installed on my Windows 7 machine.  To resolve this problem, I downloaded and installed the Windows Identity Foundation Pack.