Non of our users can login with IE. I've narrowed it down to IE not accepting cookies and the session cookie.

The only way to get it to work is to clear the session cookie in ie9 developer tools, then restarting the browser. Or letting the session cookie expire, then trying again.

I've tried everything even comparing another site that works just fine. I've also seen other posts of people having similar issues, but there is not solution.

Can anyone help? I have a client that needs this to work so his customers can login.