[rdoust]

I develop a website for my company. Our outward facing website requires that our customers identify themselves by logging in if they want to do anything with their account. (I'm using Apache/Tomcat/JBoss on the backend.) When a customer successfully logs in, he/she is directed to a new page that shows some details about his/her account at the top of the page. Any subsequent attempt by that customer to do something to his/her account via the same session should work fine, and does about 99.9% of the time. However, every now and again, for no reason that I can identify, the very next request after the successful login (resulting in the display of account details at the top of the page to which their browser was directed) asks them for their login details again, presumably indicating that the browser did not send the cookie that was returned to it upon successful login. This website has been in production for over 6 years and, as I said, it only happens very rarely, but it does happen. It has happened to me in my testing environment. Can anyone tell me how I can figure out what might be going on, or if they've experienced this themselves and, hopefully, solved it? I'd be happy to provide more information if required.
Thanks.