After installing Microsoft Forefront Client Security on a server, you receive the below error when attempting to deploy a policy
to an OU.
The policy cannot be deployed
Exception has been thrown by the target of an invocation.
Attempted to read or write protected memory. This is often an indication that other memory is corrupt.
This is caused due to the version of Forefront Client Security not being supported on Windows 2008 server. You will not receive the error
on a Windows 2003 server.
BUT there is a fix. Install Forefront service pack 1. I had to install it earlier and it took less then a minute to install. No reboot was required.
For more info see http://support.microsoft.com/kb/951951