Alvin,

 This is very odd.  I used your test code.  I put the session("test") in
page_load within an if not postback block.  I included the session.abandon
in button click.

On my dev machine in debug mode via IDE:
I ran perfmon with the following counters: (ASPNET.AppRestarts,
ASPNETApps.SessionsAbandoned, ASPNETApps.SessionsActive,
ASPNETApps.SessionsTimedOut ,ASPNETApps.SessionsTotal).  I put a break point
in the session_end event.  I launched the app with tracing enabled and see
the sessionID stays constant with successive postbacks.  When I click the
button to abandon the session, (1) the perfmon counter
ASPNETApps.SessionsAbandoned increments, (2) the break occurs in the
session_end event.  However, from tracing, the sessionID is still the same
and the session data written is still there.  Only when I kill the browser
and relaunch does a new SessionID get created.

On the target web server:
Same perfmon counters active and tracing enabled.  From tracing I see the
initial "test" session var.  However, on subsequent postbacks, the SessionID
is always new and the "test" session var doesn't exist.  When I click the
button to abandon the session, the perfmon counter
ASPNETApps.SessionsAbandoned does not increment.

Summary:
Same code on both machines.  I use the copy project wizard to deploy code to
target web server.  On my dev machine, only a browser shutdown seems to
generate a new SessionID.  On the target web server, every postback
generates a new SessionID.

Serenity Now,
Anthony