prezi freezes during loading

i just received prezi (for windows) and i can not load it. when i click on exe file it starts loading but then just freeze and then "not responding". i have updated flash and adobe air but without any success. strange think is that i tried same presentation on 5 different computers - on 3 the same thing and on one first time everything was ok then today when i tried again - it is not working. on mac version everything is fine.

please help !