For years I've been using an Excel 2000 workbook (under Win XP)
containing several macros, one of which is auto-opened at launch. (It
performs necessary date checks). Security has been set so that before
the workbook opens I get a warning text box asking me if I want to
enable or disable macros.

I've just ported the workbook to Office 2007 in a new computer running
Win 7 Pro. With this system I find that when the workbook opens (in
compatibilty mode), the current worksheet and the warning bar about
macros appear simultaneously. I can accept or reject macro operation
as I wish, but even if I accept it the auto-open macro hasn't run. Any
ideas how to get round this? I'm in unfamiliar territory with no
previous experience of Win 7 and not much of Office 2007. Have I just
missed something simple?

I can't use self-signed certificates because the workbook will be used
on more than one computer.

TIA John