Jun 09, 2011 09:07 AM|GPankaj|LINK
This could be your cookie timeout happening, if you are using form authentication. On session time out the application won't redirect to a login page unless and until you check in your code some thing like
if session[somevalue] == null then
redirect to login page.
But in your case you are not using session variable at all, so I was wondering where you are redirecting.