Start by opening up Excel and go to
Window
in the menu bar and see if the "Unhide" option is available. If it is not
grayed out, click it and see if there is a Book1.xls hiding from you. If
that's the case, it's probably located a folder which contains workbooks to
always be opened when Excel opens. Track it down and kill it - or make sure
it doesn't contain some useful information/functions first.
If Unhide is grayed out, we'll have to think more on this. A starting place
would be the Excel help topic: Reset workbook and worksheet settings
