I am getting permanent error "session expired... " when submit login and password.
The problem happens with both IE and Firefox browsers and only when my comp behind firewall and proxy server.

Try the solutions listed in the login problems sticky, and post again if they don't work.

Unfortunately it does not work for me, though I tried described solution. Sometimes I succeed to login after several tries, bus session is gone immediately when I send the next GET/POST being inside already.
I faced with similar problem on different PHP based sites and the problem related to the proxy server through my computer accesses to the internet. I googled a problem and found some seems related posts.
This link is one of them

thanks

What is your handle? We can add you to a debug script that will let us know more about the cause of your problem.

My handle is 'Kwisatz Haderach'.
It works fine from my home computer connected directly (not through proxy) so it can confuse the debugging process.

If you want I can make tries at the specific time scope for making debugging easier.

thanks for you are dealing with this.

Done, please check if you can login now.

Yes, works now. Thank you very much