After Service Pack 2 for Microsoft Forefront Unified Access Gateway 2010 is installed, the portal may intermittently become unresponsive to clients.
Forefront Unified Access Gateway makes LDAP calls to Active Directory when user authentication and group membership checks are performed. In certain scenarios, some of these calls may get stuck in an infinite wait state. Eventually, this problem could lead to a deadlock situation in the Forefront Unified Access Gateway environment.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.