Even though Microsoft updated its office suite for Mac Not long ago in order to add new functionality, it seems that developers missed fixing some problems with Office for Mac.
To put an end to "these critical problems" Microsoft has published the version 14.2.1 of Office 2011 for Mac that applies to all programs and versions of the office suite.
Given the drama of this update, it is recommended that all users of Office 2011 for Mac apply this update as soon as possible, for this, you only have to access the web page that Microsoft has published for the occasion.
More information - Microsoft Office 2011 SP2 Now Available
Download - Microsoft Office 14.2.1 Update 2011