To resolve the problem, you can take the following steps:
Open Outlook.
Click on Tools.
Click on About Microsoft Outlook.
Click on the Disabled Items entry.
You will see a Disabled Items window open, with the following information within it:
The items below were disabled because they prevented Outlook from functioning correctly.
Please note that you may have to restart Outlook for these changes to take place.
Select the ones you wish to re-enable.
If you see "Addin: outex.dll (outex.dll)" listed, click on it to highlight it and then click on the Enable button. Then click on the Close button. Then click on the OK button to close the About Microsoft Office Outlook window.
You should then be able to click on Tools and then Out of Office Assistant to modify the out of office setting.
When I employed the procedure and then checked the registry afterwords, there was no longer a Resiliency subkey. The outex.dll DLL, which is apparently used by the Out of Office Assistant, was the only disabled item. The key that had been in the registry is listed below:
[HKEY_CURRENT_USER\Software\Microsoft\Office\11.0\outlook\Resiliency]
[HKEY_CURRENT_USER\Software\Microsoft\Office\11.0\outlook\Resiliency\DisabledItems]
"437C9368"=hex:01,00,00,00,14,00,00,00,14,00,00,00,6f,00,75,00,74,00,65,00,78,\
00,2e,00,64,00,6c,00,6c,00,00,00,6f,00,75,00,74,00,65,00,78,00,2e,00,64,00,\
6c,00,6c,00,00,00