1. Well...I don't even recall talking to you before all that much, and I certainly didn't know you were watching the episode--or that it was even called that--so...sorry? :p
2. AGAIN I must ask what the hell the point of a time machine is if you can't alter the event, it's liked the Fixed Point business, it's dramatically convenient, yes, but not altogether logical structure-wise, which annoys me--I'm not looking for TOO much logic in a show about a 700 year old guy time traveling everywhere, but something as basic as that sort of "go back and fix things" logic should at least be adressed more intelligently, rather than the storybook equivalent of "because his time machine just can't. OK?"
3. BESIDES THAT, it doesn't seem like even THAT should be an impediment--you don't have to travel back to the event ITSELF to warn yourself or fix things, jsut far enough back that your warning will precede the event. Say the Doctor has a friend, Manny McExpendable, and Manny dies in a Dalek attack in 2151 on a planet the Doctor just happened to pick to vacation on at the moment. If he can't go back a few minutes and undo the death, why not go back, say, 5 years before the he ever made the trip AT ALL, stop by his former self, and just say, "Hey, dude, don't go to X place in 5 years...Manny will die if you do. Thanks, your pal...yourself." Why not?
4. Likewise, why not just go back to a time when the Doctor's great-great-great-great grandparents were off that planet and then kill THEM, thus preventing his existence?
5. But he messes with events all the time--just when its convenient.
6. But if points before fixed points are fixed, and back and back, it would follow that ALL OF TIME IS FIXED, fatalistically...so you can't have it both ways, Doctor Who: either time can't be changed and is fixed, in which case the show would be pretty boring, or else time is changeable, and in THAT case, get rid of this Fixed Points nonsense, and just go back to the 9/11s and Pearl Harbors and Pompeiis and such of history...come on, the show's been on for nearly 50 years, why not? Sure, it could be challenging to write, but EVERYONE would be interested in such stories, and after 50 years, I think you have some leeway yo do something different.
6. I STILL have no idea what that River girl is all about...except she's annoying, and the Evil Trashcans are much preferred. :)