sess_destroy

[eluser]PhilTem[/eluser]
Like @Aken said it's a browser cache issue. If you don't want browsers to cache your page on every forward/backward AND reload action (the browser will use its cache as long as it's not expired) just add an appropriate HTTP-header (keywords pragma as well as cache-control, see wikipedia) to each page. Then it should get "fixed".

But be careful since this method might slow down page loads for the user and increases load on your server since every file has to be submitted again (like css, js, images) if you don't specify their TTL explicitely.