Many people have reported a problem with Microsoft Outlook 2011, where they cannot create new messages or send messages in the outgoing queue. Clicking on the New and Send buttons do nothing, and traditional troubleshooting steps do not help.
This problem is linked to the fact that Outlook 2011 now uses Webkit to display HTML messages. Since Webkit is the open source engine used by Safari, if Safari is having problems, these can trickle down to Outlook.
The solution for this particular problem is to quit Outlook and reinstall the latest version of Safari found HERE. Going forward, reinstalling Safari may become a common step for resolving Outlook 2011 issues.