I swear I thought I was making this up.
I recently stumbled across a YouTube video at Fark.com, featuring physicist Michio Kaku talking about time travel:http://cgi.fark.com/cgi/fark/vidplayer.pl?IDLink=3627628
His solution to the risk of creating paradoxes by 'going back in time and changing something that would keep you from going back and making the change' is that traveling back in time creates a new "branch" on the timeline. So the grandfather you kill is never your own grandfather; he's the grandfather of your identical twin on a separate timeline.
This is pretty much how I eliminated time travel paradoxes in V&V, and still do in Living Legends (though I express it in terms of those parallel timelines already existing as parallel universes, rather than being created when you travel there).
Now, I'm no physicist, but I try to keep myself informed, and I have to say that Michio Kaku sounds awfully certain that this is the "official" current view in physics. As far as I've ever seen, theoretical physicists are almost never in that much agreement. Still, it was cool to hear the bullshit I thought I was making up get kind of supported by a real physicist.
-Jeff Dee