I have my own thoughts on this idea of yours that is different than most, however, until November is over, I don't have the mental energy or time to put thought to keyboard.
James, who likes the timeline protection theory. Time really doesn't like change. Anything the traveler does will ultimately bring about no change as time will attempt to heal the damage.
Example: Man goes back in time and kills his grandfather. He goes forward and finds out that the man wasn't really his grandfather.
My take on it though is that it would take a really big change (setting off a nuclear bomb at Little Big Horn) for time to be seriously warped.
http://en.wikipedia.org/wiki/Temporal_paradox#Timeline_protection_hypothesis
