An update for the Source Engine has been released.

This time the update will be again fixing bug in the Steamworks internal starts reporting and also fixing crashing in custom maps using the trigger_camera entity.

The update will also disable clients loading server plug-ins that are not signed by Steam.

Source Engine Changes (CS:S, DoD:S, TF2):

Disabled clients loading server plug-ins unless the plug-ins are signed by Steam or the client is running in insecure mode.
Added a checkbox to the Options->Audio dialog to control muting the audio when the game window is in the background.

Counter-Strike: Source:Fixed crash in custom maps using the trigger_camera entity.
Team Fortress 2Fixed another bug in the Steamworks internal stats reporting.
Updated the localization files.