Hi Paul - sounds like your workbook is shared. VBA projects are not viewable
in shared workbooks - if you unshare it, you'll be able to view the VBA code,
make your fix, and then reshare it.

If it works fine when unshared, it sounds like your user is hitting
something which isn't possible in shared workbooks (a number of formatting
options, for example, are not permitted in shared workbooks.)

Hope this helps
DS