Apologies for cross posting, I posted similar to WordVBA addins, but the
more I investigate the more it relates to Wd2003 and UserForms.

Create a template, add a UserForm1 with CommandButton1, add a Module with
Sub Main.
Sub Main code = UserForm1.Show
CommandButton1 code  below
Private Sub CommandButton1_Click()
   Dim sFile As String
   sFile = "<any valid document path & name>"
   Documents.Open FileName:=sFile
End Sub

Save Template
Close Word
Open Word (so there is a Document1 created)
Tools - Add templates - add your template globally.
Tools macros - Run "Main" - click on CommandButton1 and you should get
error:
"Run time error 5479 You cannot close Microsoft Office Word because a
dialog box is open.  Click OK, switch to Word and then close the dialog
box."
Where am I trying to Close word?

This will not happen if:
I do not have a clean Document1 created by opening word, type something in
Document1 - OK, Create Document2, close Document1 - OK, close Document1
(leaving no documents open) - OK, I do not load the template globally but
run from the open  template - OK, I run Main a second .... time - OK.

It will go away with:
Me.hide
Documents.Open FileName:=sFile
Me.show

I have gone back through Word 2002, Word 2000 neither of which show this
anomaly.

Any suggestions apart from the Hide/Show as a work around and as to why the
problem is so specific.

TIA

Ian B