OWA users logging off OWA are prompted for credentials after pressing the logoff button, how can we correct this? This only occurs when connecting the front-end server.

This issue is likely caused by a miss-configured authentication setting on the exchweb/bin folder in IIS. On a front-end server the Exchange, Public and exchweb/bin folders should be configured for Basic Windows authentication. A misconfiguration can cause multiple login prompts.

For more information refer to https://support.microsoft.com/kb/325906/en-us