Not sure how I missed this, but the heliosphere is a lot smaller than current predictions. No object has ever made it out of the heliosphere, the protective magnetic bubble of our sun since we began our space age. If the penetrating of the bubble somehow causes a rip which has some sort of CME/flare effect from interstellar space with the interstellar matter which is hot as this wikipedia article shows;

The Local Interstellar Cloud (or Local Fluff) is the interstellar cloud roughly 30 light years across through which the Earth's solar system is currently moving. The Solar System is thought to have entered the Local Interstellar Cloud at some time between 44,000 and 150,000 years ago and is expected to remain within it for another 10,000 to 20,000 years. The cloud has a temperature of about 6000 °C,[1] about the same temperature as the surface of the Sun.
[link to en.wikipedia.org]

And somehow causes the 2012 doomsday scenario and no one would see it coming. Wouldn't that just be so ironic, so many people expect an asteroid or some outside force to be the cause but in the end it could be our own actions that cause a chain reaction that leads to our own demise.

ScienceDaily (June 15, 2011) — Scientists analyzing recent data from NASA's Voyager and Cassini spacecraft have calculated that Voyager 1 could cross over into the frontier of interstellar space at any time and much earlier than previously thought.

The analysis indicates that the boundary between interstellar space and the bubble of charged particles the sun blows around itself is likely between 10 and 14 billion miles (16 to 23 kilometers) from the sun, with a best estimate of approximately 11 billion miles (18 billion kilometers). Since Voyager 1 is already nearly 11 billion miles (18 billion kilometers) out, it could cross into interstellar space at any time.
[link to www.sciencedaily.com]