A lot of Outlook issues are caused by various add-ins. So, disabling all add-ins is a useful step and should be the first step for Outlook troubleshooting. Please note every add-in will be a subkey under the following subkeys. HKEY_LOCAL_MACHINE\SOFTWARE
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Read the complete post at http://blogs.technet.com/asiasupp/archive/2007/01/16/outlook-troubleshooting-first-aid-disabling-add-ins.aspx