I am using IS_AJAX but sometimes still get disconnects

[eluser]WanWizard[/eluser]
Problem is that if you have multiple concurrent requests, you can still run into the situation that a request rotates the session id, while the parallel request, that took longer to process, writes the old (and now obsolete session id back to the cookie).

It's not a fix I posted, but a clumsy workaround, which stores the old session cookie as well, and tries a match on both. Search my post history for the solution.