Using Office 2003 and Windows XP;

This seems odd to me, but it seems that sometimes Application.Quit will shut
down a second running instance of Excel. I haven't thoroughly tested when
this occurs.
Am I just mistaken and/or confused having more than one instance running or
is this by design based on which instance happens to be active when the code
runs?

Is there a way to ensure the desired effect by returning a reference to the
current instance and quit only that one? Is it possible to use something like:

ThisWorkbook.Application.Quit

Could someone please help me out with some example code and discussion on
this?

Thanks much in advance for your assistance.