Microsoft has released Office for Mac 2011 14.5.1 Update.
This update fixes critical issues and also helps to improve security. It includes fixes for vulnerabilities that an attacker can use to overwrite the contents of your computer’s memory with malicious code.
This update fixes an issue that causes the main window not to open in Outlook for Mac 2011.
Applies to: Office 2011, Office 2011 Home and Business Edition, Word 2011, Excel 2011, PowerPoint 2011, Outlook 2011, Office for Mac Standard 2011 Edition, Microsoft Office for Mac Home & Student 2011, and Microsoft Office for Mac Academic 2011.
More info and download link here.