I've always wanted to say that ;)
Stephen Hawking is being quoted in the media as saying that the Higgs Field could wipe out the Universe. His point is that at a high enough energy, it could trigger what's called "vacuum decay," a state whereby a "bubble" of vacuum expands at the speed of light, destroying everything in its path. This could happen if the energy of the field is not constant and eventually changes or, as some media are reporting, if a sufficiently-advanced civilization were to experiment at such high energies.
To do this would require a linear accellerator, as we understand them, the size of the orbit of the Earth. Not something we're about to build any time soon.
Here's why everyone is wrong, at least about the second part: if it could have happened, it would have by now. Indeed, anything that any civilization could do to destroy the Universe would have resulted in such destruction long ago. The Universe is huge. If something could have happened, it would have. To think that in the 13.7 billion years that we think the Universe has been here NOTHING capable of destroying it has happened yet, but just might any day now is the pinnacle of self-importance. The odds just aren't there.
So relax. The Universe will be here tomorrow. I'm prepared to bet on it, in fact ;)