Many of you probably know that you can get rid of The application-specific permission settings do not grant Local Activation permission for the COM Server application with CLSID {61738644-F196-11D0-9953-00C04FD919C1} message by changing the permissions for the IIS WAMREG service in the DCOM Component Services Administrative Tool (Administrative Tools > Component Services, navigate to My Computer > DCOM config).
If you’re working in Windows 2008, there is an extra step that you need to go through. Whereas it was possible to modify permissions out of the box in Windows 2003, in Windows 2008, you must change ownership of registry keys before you can change permissions. This blog has more information:
http://www.wictorwilen.se/Post/Fix-the-SharePoint-DCOM-10016-error-on-Windows-Server-2008-R2.aspx