Last Updated: April 18, 2018
When clicking on items in the Conversation History folder, Outlook hangs or shows the "Not responding" error message. The issue may also occur when clicking on Skype items and email voice mails.
When Outlook encounters a certain combination of errors trying to resolve a message class, Outlook will go check the Organizational Forms library on the Public Folder server to ensure the correct message class is available. This introduces an extra call out to the Public Folder server to resolve the message class. Due to delays in Autodiscover and public folder response times this can cause Outlook to hang. An example message class from recent reports is IPM.Note.Microsoft.Conversation. This problem can also be exaggerated if the Public Folders are not optimally configured or if they are on older unsupported versions of Exchange 2007.
Support has identified two possible client side workarounds. Each of these eliminates a default Outlook function and largely or fully eliminates the hang:
The full registry path, DWORD, and value for each follows:
Reference KB 2212902
Disables Organizational Forms Library functionality in Outlook.
Your organization may use some of the above functionality and it is recommended to test or deploy the workaround to a subset of users first to confirm it mitigates the issue or if it causes any unintended consequences.
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