I very often will save a drawing file in PDF format but before I can re-open the drawing file I have to close my SW2016 or I get an error message " NAME.SLDDRW is being used by another user. Do you want to open a copy?". There are no other users I have a stand alone license. I have to close Solidworks then re-open it before I can re-load the original file. Is this a Solidworks issue or a windows issue? Does anyone have a recommendation on how to fix it?

Thanks!!