ows Xp and Autofilter in Excel

I set up a spreadsheet for a colleague and inserted some code into Visual Basic Editor in Excel so that the Autofilter would work even when the workbook was password protected. The spreadsheet worked fine until all our systems here were upgraded to XP Pro (we were previously running Windows 2000). I've run out of ideas of which way to fiddle with the code to get it to work again. Is there anything in XP that I can shut off or alter to get the spreadsheet working again?
Thx