Session randomly disappear

Hi,

We are using Code Igniter 2.2 on one of our internal website and it has grow very large now. For a long time it has been working fine with the exception of sessions got destroyed randomly. It is a small problem to us as we are all programmers here but soon we will be rolling the system to everybody in the company which includes a lot of less nerdy people so this session bug will become an issue.

I learnt that upgrading to 3.x will fix the problem but that will be a huge project to us and given the framework has no other issues other than this we would like to avoid upgrading it as much as possible. 

I have tried a lot of suggestions on the internet including setting the time out to a specific number (cant remember what was the magic number now but it didnt work anyways), set time out to 0, set $sess_expiration in Session.php to a supper large number, setting $cookie_secure to false, commenting out the whole session_destroy() function in Session.php...

Im just wondering if there is a patch or walk around that we can apply instead of upgrading as we are very happy about the framework as it is right now.

Thanks in advance.