The month you were shown as not hitting 100% - I think it was because you started a puzzle just before midnight of the last day, but did not finish it until after midnight. You are charged with the attempt when you load the puzzle, but not credited with the win until the system verifies that you completed it.
If you look at the monthly scores - particularly completion percentage, you'll see people who are in the middle of puzzles shown below 100%. I remember that month and seeing you still doing puzzles as midnight neared. I stopped just in case a puzzle took me past midnight, since I could not move up in the rankings with another 20 or 30 puzzles anyhow.
I glance at my totals after nearly every puzzle and stop to record them every ten puzzles. I have been lucky and not had the site go down on me. I've also had to stop doing puzzles if I see a thunderstorm approaching, just in case my power goes out - as it did one time, though I got it back in time to complete the puzzle.
Luck helps, but being careful doesn't hurt. I'm sorry for all the people who've gotten tripped up by snafus recently. After Kat's problem, I've taken to logging out of this site if I'm going to be away from my computer for very long.
I wish better luck to all, and good puzzling.