Excel found unreadable content
 

I recently was upgraded to Excel 2007, when I try to open my spreadsheets
that have large pivot tables I get the Excel found unreadable content error I
can click on yes to recover however my pivot tables are no longer pivot
tables they are just the values in a cell. If I open up the spreadsheet in
Excel 2003, no error and the pivot tables are still functioning.

Any ideas what I can do?