http://blogs.msdn.com/b/spatdsg/archive/2010/02/10/wsfederationauthenticationmodule-auth-failure.aspxAs you may have guessed from my recent posts, I was working on a first stab at some WIF work recently.. and the app was failing with the following error. The system cannot find the file specified. Description: An unhandled exception occurreden-USTelligent Evolution Platform Developer Build (Build: 5.6.50428.7875)http://blogs.msdn.com/b/spatdsg/archive/2010/02/10/wsfederationauthenticationmodule-auth-failure.aspx#10132528Tue, 22 Feb 2011 07:19:09 GMT91d46819-8472-40ad-a661-2c78acb4018c:10132528Doc WattsMan<p>See <a rel="nofollow" target="_new" href="http://consultingblogs.emc.com/simonevans/archive/2010/11/19/common-windows-identity-foundation-ws-federation-exceptions-explained.aspx">consultingblogs.emc.com/.../common-windows-identity-foundation-ws-federation-exceptions-explained.aspx</a> for your answer. Set &quot;Load Profile under Application Pool &gt; Advanced Settings, or implement code to change the crypto provider to one that does not depend on the machine key.</p> <div style="clear:both;"></div><img src="http://blogs.msdn.com/aggbug.aspx?PostID=10132528" width="1" height="1">