SAMLIdentityProvider.InitiateSSO Method is not supported.

We are testing an IdP and Sp on our system. When I place the IdP on my local machine, it works fine. Once I placed it into Windows Server 2008 we receive an error on the Default.aspx page when I click the “SSO to the Service Provider”, this button click calls the SAMLIdentityProvider.InitiateSSO method.

Has anyone encountered this or have any light they can shed on this issue. The server has all the latest updates (see below)

If running Windows Server 2008 and an error is encountered attempting to generate SHA-256 signatures, please ensure the following.
1. All Windows updates have been applied including <ahref=“https:”" en-us=“” library=“” security=“” 3033929.aspx"=“” style=“color: rgb(0, 0, 0); font-family: Arial; font-size: 13.3333px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: 2; text-align: left; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(255, 255, 255); text-decoration-style: initial; text-decoration-color: initial;”>
2. .NET framework v4.5.1 or later is installed. This is required even if your application targets an earlier version of the .NET framework.

Typical errors include:
1. CryptographicUnexpectedOperationException: Required object identifier (OID) cannot be found
2. NotSupportedException: Method is not supported
with System.Security.Cryptography.Xml.SignedXml.ComputeSignature in the call stack.</ahref="https:>