As of early AM June 28th 2012, there have been many reports of TMG services stopping unexpectedly. We are primarily seeing the issues in an SSL Publishing scenario. You may expect to see the following in the Application Event Logs coinciding with the service stopping:
Source: Service Control Manager
Event ID: 7034
The Microsoft Forefront TMG Firewall service terminated unexpectedly. It has done this <times>.
Source: Microsoft Forefront TMG Firewall
Event ID: 14057
The Firewall service stopped because an application filter module C:\Program Files\Microsoft Forefront Threat Management Gateway\w3filter.dll generated an exception code C0000005 in address <hex_address> when function CompleteAsyncIO was called. To resolve this error, remove recently installed application filters and restart the service.
It has been determined that applying TMG SP2 Rollup2 will resolve the issue. To install Rollup 2 please refer to the following link:
Rollup 2 for Forefront Threat Management Gateway (TMG) 2010 Service Pack 2
More information will be provided as it comes available. Thank you for your patience in this matter.