Towards the end of June 2012, we started to see many reports in various forums, LinkedIn Groups, and twitter, about the Forefront TMG Services stopping unexpectedly. These issues had the corresponding events in the Application Event Log:

Source: Service Control Manager
Event ID: 7034
Level: Error
Description:
The Microsoft Forefront TMG Firewall service terminated unexpectedly. It has done this <times>

And\Or

Source: Microsoft Forefront TMG Firewall
Event ID: 14057
Description:
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 when function CompleteAsyncIO was called. To resolve this error, remove recently installed application filters and restart the service.

These issues were primarily seen when using TMG’s Web Publishing feature to publish an SSL site.

On June 29th, the Forefront TMG Team announced that Rollup 2 fixes the issue. See the original announcement here: TMG Services Stopping Unexpectedly

If you’re experiencing these issues, download Rollup 2 for Forefront Threat Management Gateway (TMG) 2010 Service Pack 2 here:
http://support.microsoft.com/kb/2689195.