XLM macro dialog.box command

I have a bunch of Excel 4 XLM macros, and was thrilled to discover that
they
still work in Excel 2008, except... I can't get the dialog.box command to
work -- crashes the program ("Excel has encountered a problem and needs to
close").    I thought it might be because I wasn't specifying
size/location
(first row of dialog box definition table is blank in most of them), but
putting in some values didn't help; still crashes.  Happens in Leopard and
Tiger, but it has always worked fine under all previous versions of Excel.
Anyone else encountered this, or have any explanation/solution/workaround?

thanks!

kevin