We are in the process of switching over to Office 2007 from Office
2003 in our office. Right now only a handful of people have made the
change.

There is a spreadsheet that was created in Excel 2003. It's quite a
complicated spreadsheet with pivot tables and several worksheets. This
file opens fine in Excel 2003, updates the pivot tables and works
great. However, when opening it in Excel 2007 the error "Reference is
not valid." pops up. No other error, and the pivot table does not
work.

I have tried selecting all of the add-ins and also enabling macros and
nothing seems to help. I have also done a "save as" and tried to save
it in all of the possible formats and still the same thing happens.

Anything else I should try? Has anyone else encountered this?