Active Workbooks in Excel 2000

I have a user that recently lost view of all active workbooks on the taskbar and using Alt-Tab to switch tasks. All it brings up is the Excel App icon and then she has to go to Window and select which workbook she needs of all she has open.
Checked all the settings under Tools/Options and didn’t see anything unusual.
She hasn’t had anything loaded onto her machine within a week of this happening (Publisher was loaded last week).
Word displays all active documents as normal.