Hey Cemeskinazi,
first of all, thank you for the purchase!
The issue you’re describing hasn’t been reported previously, and the Sensei demo currently runs on the latest version of WordPress (3.7.1). It is thus very probably something server-specific or settings-specific going on. I will gladly help you to troubleshoot the situation, yet before you provide me the login data, could you please, having Sensei activated, try disabling all plugins (the “Plugins” admin section) and refreshing the admin interface; in case the issues disappear, try enabling the plugins one by one in order to find the “culprit”. Once done, please let me know of the results. Thanks!
Sincerely,
Andrii / Satori Studio