I have several problems with Cataclysm

First of all I can barely open the game, because it says '' Cannot stream required archive data. Please check your internet connection'' and sometimes I somehow get past this but it isn't permanent ( I disable my firewall and stuff ) and in game there's always a yellow circle at top of the game saying Important game data is downloading right now or something. And I also can't play as Blood Elf / go to their starting area, game freezes at loading screen. If anyone helps me with my problems, I'd be grateful, thanks in advance!