I think the main problem with peoples' view of CERN is that they think CERN is doing something completely new. The fact is, Fermilab has been doing the same thing for 30+ years. CERN is just going to slowly up the energy level to about 10x what Fermilab topped out at.
The other problem is that people don't understand the terms flying around. Words like tevatron, large hadron, high-energy particle accelerator and 'energy level of the Big Bang' lead people to think that this is the next step past nuclear bombs. What they really need to understand about colliding protons at energy levels of a trillion electron volts is that an electron volt is pretty much the smallest way to measure energy that we use, and the collisions only involve two protons. Seriously, you should be more worried every time you get your teeth x-rayed.
It's absurd to think that they'll hit a tipping point where the energy being put in will be enough to blow up the Earth. It's absurd to think that they could create a micro black hole that would engulf the Earth (if micro black holes are actually possible, AND could engulf a planet, then the universe would be dominated by them).