I have some times the same problem and i've vista and McAfee.
McAfee sux when you are installing warrock.
But i can help you for that: Go to McAfee==>Advanced Menu ( or something like that, near McAfee Personal Firewall ). After go to configure. After at the left clik on Computer or Files ( or something like that, the second choise ). And after turn off you antivirus for 15min and when the upload of the new version is finish, turn it on.
Go to play and own noob :P
KD CA:1.44
KD WR: 1.64
CA is very easy when you have good weapon ( m4/m416CQB/m590 mariners ) and the game is beautiful. But i prefer warrock cause there is some md500 :P