I was able to get it to repro in Excel 2003 following these steps:
-Have 2 workbooks open
-Switch on "Windows in Taskbar" under Tools, Options, view
-Switch between the workbooks a couple times using the workbook buttons in
-Close the workbooks.
Looks like a bug, albeit a small one.
| It did for me using winXP home and xl2003.
| > You can minimize Excel and other apps by clicking their icon in the task
| > except Excel won't minimize if you don't have any spreadsheets open.
| > Frustrating to get accustomed to a feature that sometimes doesn't
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| Dave Peterson