I’ve worked in a customer that started to get the system unavailable message message in all the webservices after a ForeFront installation.
Some of the symptoms:
Three of the Application Pools on the IIS Services manager are stopped and we cannot start them
OWA, Autodiscover, OAB returns the same error message: System Unavailable
Event ID 2268 and 2274 with source W3SVC-WP
Then, what’s the problem? How can I solve it? Here is the Microsoft KB to solve this issue: http://support.microsoft.com/?id=894435