I use Excel 2003 in Windows Vista.
Application.StartupPath & "\personal.xls" is hidden, holding VBA code.

On closing Excel after changing code, I get the invitation: "Do you want
to save the changes you made to the Personal Macro Workbook? If you
click Yes, the macros will be available the next time you start
Microsoft Office Excel."

Occasionally, I instead get:
"Do you want to save the changes you made to personal.xls?".

This is because I UNINTENTIONALLY unhide the hidden file.
The correction is easy - click Window/Hide.

I would like to know how to detect the operation that unhides the file?
I hope the answer to this question will be generally useful.
--
Walter Briscoe