For Document Transformations in Alfresco ie converting a document from one format to another(Eg: Docx to PDF, JPG to TIFF, etc..), Alfresco internally uses Open Office(OO) &Jod converters . Looks like with the OTB Alfresco Ent 4.0,2.9 Windows installer there's a problem that prevents/skips OO from being installed as a service(its called alfrescoOpenOffice on Windows services). The fix is to run the below script as Admin & the alfrescoOpenOffice service should get installed.
\alfresco\openoffice\scripts\openoffice_serviceinstall.bat
Once installed, make sure its always running if you'll be doing document transformations. Hope that helps!
Thanks,
Somu