I see exactly the same thing. My big spreadsheet goes into recalc mode
and for a number of seconds seems to spontaneously open another window
as part of its recalc effort, and then closes it before finishing.

I assumed it might relate to something like:
- caching the spreadsheet (even though I have ample memory for it)
- shared .xls needing to save some interim image during recalc
- something to do with being able to save "undo" information in
case you decide to undo
- references to other spreadsheets which, even when those .xls are
closed, can involve building a clone .xls with saved data from it so
that it can be used.

So I really don't have any idea what it is doing.

Craig in NJ

On Oct 26, 10:58 am, "Adrian D. Bailey"
wrote:
I have a large suite of workbooks with multiple sheets and macros, basically
all working, but.....

Some of the macros take a long time, and involve loops etc. I have arranged
for most of my macros to write to the Status bar to keep me informed of
progress.
This was written in XL2000, and worked just fine.
Now I've upgraded to XL2003, and whilst the macros works, some strange new
things are happening!
At some point during execution - and it's not always the same point - a new
sheet appears minimized on the taskbar. The icon on the active window (at
the top left of the window) changes to a plain white recangle, and the
status bar stops updating. When execution concludes the new window closes,
the proper XL icon returns, and the status bar clears (as it should because
I've written that into my macro).
If I hover the mouse over the new window on the task bar, the tooltip tells
me that it has the same name as one of the other already-open workbooks.
Dependent on which of my macros is running and/or which of my books is the
active book, different duplicate books are opened.

What's going on? And how might I stop it?
--
Adrian D.Bailey, Information and Systems Manager, Dept.Human Sciences
Loughborough University, Loughborough Leics, LE11 3TU, UK.
Tel: 01509 223007 Fax: 01509 223940

Community Warden, Storer and Burleigh Areas. Out-of-hours Tel: 01509 563263
--