I am running Outlook 2010 on Windows 7 Pro x64 on a domain. Outlook is connecting to exchange, and the username and password should be pulled from my logon credentials.

The problem is, about every few hours, outlook "forgets" what my password is. In the taskbar, a caution triangle appears, and in the bottom right hand corner of exchange, a "Needs Password" replaces "Connected to Microsoft Exchange." Simply clicking "Needs Password" fixes the issue, and new messages are downloaded.

What could the issue be? What could be timing out?

Edit: Also, at times the following window appears:

This is my Security Settings