XL2003 on XP

Im working in a network environment where upgrades of operating system and
application packages are automatically downloaded overnight so users need
take no action to have the latest versions available. I have several Excel
applications in which the macros do basic password protections to user files
so that formulas are not accidentally overwritten:

For Each ws In ActiveWorkbook.Worksheets
ws.Protect Password:="", UserInterFaceOnly:=True
Next

Up to 3 months ago they worked fine. I dont know just when things changed,
but now the password protection is applying to my macros as well, in spite of
the argument. Can anybody explain this? Is it possible that the system
admin has changed user permissions in some way that overrides the argument?

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Al C