http://blogs.flaphead.dns2go.com/archive/2007/08/07/forefront-security-for-exchange-server-fails-in-a-single-copy-cluster-environment.aspxDoh, looks like the an old antigen issue has crept in. Source: http://support.microsoft.com/kb/939365 Anyway, you should try an get this fix, as it's a FULL installation, all 30ish MB It gives you version 10.0.0701.0, which is later than rollup 1 AlsoenCommunityServer 2.1 SP2 (Build: 61129.2)http://blogs.flaphead.dns2go.com/archive/2007/08/07/forefront-security-for-exchange-server-fails-in-a-single-copy-cluster-environment.aspx#8639Wed, 08 Aug 2007 08:24:21 GMTdfd37a73-98d8-4eec-a8b7-87a183efa840:8639Carpe Diem: Flaphead.com @ Home<p>Just an update from my previous blog . Computer Says no, well it actually still says Could not start</p>