I travel a lot and very often work in Internet-cafes. In some places I noticed that pages are being cached in proxy-servers memory to minimize traffic. This make almost impossible to write to the forum, because after posting you see the older (saved) version of the page. This may also cause login problems.
There is a very easy way to solve this caching problem. You just have to add the following to your index.php file:
header('Expires: Mon, 26 Jul 1997 05:00:00 GMT');
header('Cache-Control: no-store, no-cache, must-revalidate');
header('Cache-Control: post-check=0, pre-check=0', FALSE);
I have done this a few months ago and everything works fine.