[eluser]slowgary[/eluser]
I think I understand the issue, will anyone confirm? It's more of a race condition than anything, but it just so happens that the conditions are more likely repeated for applications that have many concurrent AJAX calls, which mine does.
Anytime two requests are returned in a different order than they are sent, your application has the potential of destroying the session (if the regeneration happens after the first request). Since AJAX is asynchronous, there are plenty of opportunities for this to happen. In my application, I'm making two AJAX requests at the same time, one of which usually takes longer since it returns more data.
The proposed solution above will decrease the likelihood of this problem occurring for AJAX heavy applications, but in applications that serve assets this could also creep up. It seems that CodeIgniter's Session library is not suitable for applications that require concurrent requests from a single user. This is unfortunate.
