Macro error after switching from Excel 2000 to Excel 2003

My company recently switched from Excel 2000 to Excel 2003 and now a macro I
created does not work. It gives me the error 1004 and highlights the line of
code where I set it up to open certain files in a folder. This macro has
been working for 6 months without fail and only has problems opening the
Excel files I created after the switch to 2003. Any help would be
appreciated.

Without any other info the only suggestion is to see if your sheets
have different names.
For example, a statement like:

Sheets("Feb Sales").Cells(i, j+5) = k

might cause a 1004 error if the new workbook does not have a sheet with
this name. Otherwise you need to post the code.

HTH
Kostis Vezerides