out-comment the security update is not the best way i think. i was using these lines for my older 3.3 install of knoppix and it worked fine for me (i got all the security updates with apt-get update | apt-get upgrade)

i havent tried 3.4 yet. hopefully this evening though. but i will setup apt again because is the easiest way to keep your system up to date. no need for installing security patches the manual way or smth.