Yesterday on the 28/06/2012 we started receiving the following alert across multiple TMG servers which were on TMG SP2 with no rollup.
The Microsoft Forefront TMG Firewall service terminated unexpectedly. It has done this 3 time(s). The following corrective action will be taken in 60000 milliseconds: Restart the service.
We’re not sure of the root cause of the issue at the moment but the fix is to update your TMG to SP2 Rollup 2. The download link is as follows “http://support.microsoft.com/kb/2689195”