If your WebOffice Sample project does not run at all and you get error log entries in WebOffice.log like
com.esri.arcgis.interop.AutomationException
or
com.esri.arcgis.interop.Dispatch.vtblInvoke
then please check if the Windows Firewall or another Firewall is active. Deactivate the Firewall.
This error may occur with Windows 2008 Server or Windows Vista 32/64 Bit because Windows Firewall is active by default on these Operating Systems.