Some security settings changed on the site?

I’m getting this standard bull both here and at work now when hitting ‘back’. No settings have been changed on either machine sio I guess it’s something been changed on the site?

Webpage has expired

Most likely cause:
The local copy of this webpage is out of date, and the website requires that you download it again.

What you can try:
Click on the Refresh button on the toolbar to reload the page. After refreshing, you might need to navigate to the specific webpage again, or re-enter information.

 More information 

If you continue to have this problem, try the following:

In Internet Explorer, click Tools, click Internet Options, and then click the Advanced tab.
Scroll down and uncheck the “Do not save encrypted pages to disk” option in the Security settings.

I thought that was normal as i alway get that when i press back button ??

I have too press back then refresh screen…