I haven't heard of this happening. If you hold the Alt key and click on
something in Word, that generally opens the Research pane. Could there be
something peculiar in how you're opening Word?
Does it happen all the time? For example, does it happen when you
double-click a document? Or does it happen only when you use a shortcut to
open Word? Or, are you using a keyboard shortcut to start Word?
Does it happen if you start Word in safe mode? Hold the ctrl key when
starting Word, then click Yes to prompt about starting in safe mode.
It would help to know what version of Word and Windows you are using.
>> Stay informed about: Research Pane Opening when Word is launched