In a Microsoft Forefront Unified Access Gateway 2010 array deployment, Web Monitor may not display some security events in the Event Viewer window. This issue may occur after some user request receives an "Invalid HTTP request version" error message. This error is reported in Web Monitor as "Warning #18: Invalid Request Version."
This issue occurs because Web Monitor may incorrectly parse the XML query and not display some logged events after a "Warning #18: Invalid Request Version" HTTP event is reported. This issue occurs only in a Unified Access Gateway array deployment.
To resolve this problem, install the service pack that is described in the following Microsoft Knowledge Base article:
2710791 Description of Service Pack 2 for Forefront Unified Access Gateway 2010
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
For more information about Web Monitor, go to the following Microsoft website: