[thelist] ASP - Application never unloads

I've this application that loads a whole bunch of Application
level variables when Application_OnStart (I know, I know,
but I'm just maintaining this thing, I didn't write it).

So, I'm thinking, every night the application should unload
after every session has timed out, but it doesn't.  Furthermore,
trying to explicitly unload the application ("Unload" button in
MMC for the app properties) doesn't unload the application 
either.

The only way I can unload the application is to modify the 
global.asa file which expires all sessions and unloads the
application.

In short, can someone help me understand what I have to
do to get the Application to unload in IIS?

Thanks a bunch (in advance even),
Christopher Atkins