Here's a problem which I'm really starting to think has no solution.

I have a web page that requires users to log in using FormsAuthentication. Users cannot go to pages unless they are logged in.

The problem is that when the user logs out they can click the "back-button" to see the page they were on when clicked log out. This is because the page is stored locally in the user's cache. One way to fix this is to prevent pages from being stored in the user's cache, however this means that they cannot use the back button while they are still logged in. Surely there is a way to comprimise. Online banking websites do it so it must be possible.

Basically I want to be able to log on, navigate through pages while still being logged on and be able to use the back button. If I log out and use the back button I want to be redirected to the login page.