I’m well aware of the Microsoft support base article stating that it’s not supported to automate office products UI less. It seems that Windows Server 2008 x64 and Excel
If you are using Apache, you might also need to follow these steps to get MS Word working properly (along with everything outlined in other answers):
Below is a screenshot showing the two dialogs you'll need to bring up:
For Apache:
Services->Apache->Right Click (Properties)->Log On Tab
MS Word:
Launch dcomcnfg.exe->Console Root->Component Services->Computers->My Computer->DCOM Config->Find Microsoft Application->Right Click(Properties)->Identity Tab
**if you can't find the MS Word, make sure you are launching the correct DCOM Config (64 bit vs 32 bit) depending on what version of Office you have installed.
There are two options here, you can set Apache to use Local System Account and check the checkbox to ALLOW desktop interaction. If you do this then you need to set the Identity for MS Word to Interactive User.
Otherwise, you need to set both to the same user (Ideally the user that is logged in) like shown in the picture.