When there are two versions of Office installed, such as 2007 and 365, this will sometimes happen: Every time you open Word 2007, it will pause while it goes through its “configuring” step.
In the registry, navigate to:
HKEY_CURRENT_USER\Software\Microsoft\Office\12.0\Word\Options
Then add a new DWord called NoReReg
and give it a value of 1