A Media Composer v5.5.3.7 patch is now available as of June 3, 2013 on the Avid Download Center under "Editor Patches."
This is a maintenance release and is available to all existing owners of Media Composer v5.5.x.
Macintosh installersare full installers that include the editing application and helper apps. You must uninstall your previous version using the Avid Uninstallers located in your Applications folder before installing v5.5.3.7.
Windows installers are patch installers and must be installed on top of an existing v5.5.3/9.5.3 installation. Helper applications have separate patch installers and must be run individually following the same procedure. If you have the previous patch v5.5.3.x/9.5.3.x you must uninstall it first from the Programs and Features Control Panel. Choose “View Installed Updates” to see any previous patches.
The README file is attached to this post.