The application-specific permission settings do not grant Local Activation permission for the COM Server application with CLSID {61738644-F196-11D0-9953-00C04FD919C1} to the user SID (S-1-5-21-573225893-205518295-0000000000-00000). This security permission can be modified using the Component Services administrative tool.

• Search the GUID in HKCR registry..
• 61738644-F196-11D0-9953-00C04FD919C1
• The service name for this key is IIS WAMREG Admin Service
• Load DCOMCNFG, browse to My Computer -> ” DCOM Config”
• Go to the properties of IIS WAMREG
• The permission missing was “Local Activation” permissions for the user .

 

http://www.cleverworkarounds.com/2007/10/25/dcom-fun-with-sharepoint/