Not sure if this helps, but this is may help those that have changed their default ports for their installation.
Recently began an upgrade to 6.x from 5.x and was forced to change the default ports for the 6.x installation. (changed 2222 to 2224 and 2223 to 2225 in 6.x) Began experiencing the same issue logging in and tried all the steps in this post: hxxp://support.eset.com/kb5852/
I also tried to address port conflicts from this post: hxxp://support.eset.com/kb5678/#PortConflicts
A complete reinstall corrected the problem, until I changed ports again. I was pretty confident it was a port issue. I did not find this in any of the documentation I ran across, but I did note that the process to rebuild the era folder under the Tomcat directory requested a replacement of this file: C:\Program Files (x86)\Apache Software Foundation\Tomcat 7.0\webapps\era\WEB-INF\classes\sk\eset\era\g2webconsole\server\modules\config\EraWebServerConfig.properties
Opening that file, noted that it contained the line: server_port=2223
Changed it to 2225, restarted the Apache services, and blam...started working.
