Running Office Professional 2003, Windows XP Service Pack 2.

I have a reporting application, generated from Access and outputting
via automation to Excel. I have been relying on the fact that, when
creating a new Excel Application in code, the Visible property
defaults to "false". I can then lay out the data, and reset the
Visible property to "true" at the end, with the end result visible at
that time.

That approach has been working well, until very recently. Suddenly,
the new Excel Application is turning up with the Visible property set
to "true" out of the box, and all of the ugly detail of the process is
visible. I have made no changes on my workstation that could account
for it. Rebooting doesn't fix the problem. Everything works as it
should on another workstation, running Office XP.

The only explanation that comes to mind is that Microsoft has pushed
out an update that has changed the default behaviour, but that seems
kind of unlikely, and searching brings up nothing on it. Ok, I can
set the property to "false" in code, which works (although it causes
Access to lose focus, with nothing replacing it, which looks
disconcerting).

I am a bit disturbed by this mysterious change in Excel behaviour, and
would be glad of any suggestions about cause etc.

TIA