Autofilter change opens another document!

Hi

i have a document - when i change the autofilter - it runs a macro and
opens another document.

I have looked around the personal.xls and the actual file it doing it
on - i cannot look at the vba behind the document being opened as it is
vba password protected and i have not worked out a way to get into it
(even though i have been asked to by my company as the person who built
it has now left and there are errors in it!)

thanks in advance