After upgrade to K2 2.6.8, K2 Media Manager don´t open.
My user is superuser
I send attached images

System Information

PHP Built On - Linux gator4114.hostgator.com 3.2.54 #9 SMP Thu Feb 13 08:17:11 CST 2014 x86_64
Database Version - 5.5.33-31.1
Database Collation - utf8_general_ci
PHP Version - 5.3.28
Web Server - Apache
WebServer to PHP Interface - cgi-fcgi
Joomla! Version - Joomla! 3.2.2 Stable [ Ember ] 6-February-2014 16:00 GMT
Joomla! Platform Version - Joomla Platform 13.1.0 Stable [ Curiosity ] 24-Apr-2013 00:00 GMT
User Agent - Mozilla/5.0 (Windows NT 6.3; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/33.0.1750.146 Safari/537.36

Hi. Check your page for javascript errors. You can view the errors at your browser console.

Thanks Lefteris...
I see my browser console and this is the result...
I attach an image named 'Console Output'
What do you think?

Have you modified the administrator template? I just tested under Joomla! 3.2.3 with Chrome and had no issues. Try to clean your browser's cache.

No i not modified Isis, and with Hathor is the same problem.
I test in Chrome, Firefox, IE, Opera and in all, see the problem, inclusive in other machines.

The error seems to come from template.js file. Have you enabled GZIP compression in global configuration? If so, try to disable it. Finally try to open the network tab in the Chrome development tools and refresh the page. Make a screenshot of the javascript files loaded there.

Sorry for my late answer, i'm out of the city in the past days.
I'm not activate GZIP compression in global configuration never.
The screenshots are named Network 1 and 2.

Thanks for help

There are several script files loaded there so probably this is a conflict with an other extension. Do you have any modules published in administration other than the Joomla! defaults? Also try to disable third-party system plugins until you find which one is causing the issue.