Error message when you try to open the Out of Office Assistant in Outlook 2007:
"Your Out of Office settings cannot be displayed, because the server is currently unavailable. Try again later"
This only applies to Outlook 2007 - NOT Outlook 2010
Please go to the Microsoft KB article 970123: http://support.microsoft.com/kb/970123
Scroll down to the "Fix this problem" icon and install the hotfix.
Reboot your computer. After logging in to Outlook, please allow a few minutes for outlook to sync with the Exchange server.
Click Tools -> Out of Office Assistant, the error occurs, wait another minute and try the Out of Office assistant again.