I am having issues where when ever a user logs onto a PC for the first time they go to open Outlook 2007 and it pops up with a message, 'Microsoft Exchange is unavailable.' and gives 3 options, retry, work offline or cancel. What we have been doing is then going to control panel, mail, show profiles and remove the Default Outlook Profile. Once we have done this the user can then connect to the exchange server and it functions as normal, until they go to another PC and then it has to be repeated on that PC. All PC's are running Windows XP SP3 and using Outlook 2007.

Is this Exchange 2010? If it is then you can check to see if Outlook has the Encryption enabled. Or you can disable the encryption requirement on the CAS. Details outlined in the KB below. From link: http://support.microsoft.com/kb/2006508 This problem occurs because the default Exchange 2010 configuration requires RPC encryption. However, by default, Microsoft Office Outlook 2003 does not use RPC encryption. Outlook 2007 To manually update an existing Outlook 2007 profile so that it uses RPC encryption with Exchange 2010, follow these steps: In Control Panel, open the Mail item. Click Show Profiles. Select your profile, and then click Properties. Click E-mail Accounts. Select the Microsoft Exchange Server account, and then click Change. In the dialog box that contains your mailbox server and user name, click More Settings. In the Microsoft Exchange dialog box, click the Security tab. Click to select the Encrypt data between Microsoft Office Outlook and Microsoft Exchange check box, and then click OK. MCITP: Enterprise Messaging Administrator 2007/2010 | MCITP: Server Administrator | MCTS: Windows Server 2008 Applications Infrastructure, Configuring | MCP | MCDST

Thanks for the reply, I should of mentioned that we are using Exchange 2007, would it be a similar for 2007 ?

On the Exchange 2007 CAS open up the Exchange Management Shell and type the following command: Get-MailboxServer <var>ServerName</var> | FL MAPIEncryptionRequired If the result returns True then the steps provided previously on enabling encryption using Outlook 2007 would be required. MCITP: Enterprise Messaging Administrator 2007/2010 | MCITP: Server Administrator | MCTS: Windows Server 2008 Applications Infrastructure, Configuring | MCP | MCDST