http://blogs.technet.com/dodeitte/archive/2009/05/26/the-input-file-is-not-a-valid-pkcs-7-file.aspxI ran across this issue while trying to process an offline certificate request on a OCS 2007 R2 Edge server. The certificate was issued from Comodo. When we tried to process the pending request using the OCS Certificate Wizard, we would get the followingen-USCommunityServer 2.1 SP1 (Build: 61025.2)