Opening Excel 97 worksheet in Excel 2002

I support some users that use an Excel worksheet created in Excel 97. This worksheet is linked to a number of other worksheets created in Excel 97 via SUMIF functions. When the worksheet is opened in Excel 97 on any PC with Windows 98 as the OS, the formulas calculate correctly. When the worksheet is opened in Excel 2002 or Excel 2003 on a PC with Windows XP, the formulas produce #VALUE errors. I have installed the latest upgrade for Excel 2002, and looked into any add-ins that are on the Excel 97 machines, but the formulas are still not calculating correctly. Because the formulas work correctly in Excel 97, I am trying to avoid revising the formulas themselves. Any suggestions would be very helpful.