I've been building a spreadsheet in 2003 for several months now that has
several functions and macros coded in VBA. My company just updated our MS
Suite to 2007. I'm trying to save my '03 version of the spreadsheet to the
new '07 version. I'm using the Macro-Enabled Excel Workbook because it has
macros (obviously). However, I'm getting the following error:

The name, PF1, either conflicts with a valid range reference or is invalid
for Excel. the name has been replaced with _PF1.

You may still need to manually update any references to this name used in
VBA code or as text arguements in functions. You must close and reopen the
workbook before these changes take effect.

I have PF1, PF2, ..., PF64 in column A as text. I get a popup for each
occurence. What is causing this error?