inconsistency that I thought of

[The Wrath]

In HBP, a large part of the plot is dedicated to Malfoy finding a way to smuggle Death Eaters into Hogwarts. Given what had gone on with Sirius in the previous 2 books, why couldn't they just use floo powder in the Slytherin common room?

[JMeganSnow]

Just because you can use floo powder to communicate doesn't mean you can use it to travel. Or at least, that's one potential explanation. Another is that Dumbledore might have been alerted by the use of the floo powder: since he was in on the secret of Sirius' whereabouts they could safely communicate via that method. If you recall, when Dolores Umbridge became headmaster briefly Sirius only narrowly escaped being caught.

[The Wrath]

But they do use it to travel, quite frequently. Unless there's some enchantment on Hogwarts that will let your head, but not the rest of your body through, I think it's an inconsistency.

[non-contradictor]

I'd have to agree with Jennifer's second suggestion. Dumbledore probably set up Hogwarts to allow "flooing" from No. 12 Grimmauld in case of an emergency, or just to be able to fire-call whoever was on duty at headquarters should he need to check up on things. Phineas Nigellus wasn't all that reliable of a phone-replacement.

[Qwertz]

I'm having difficulty remembering anyone who had traveled bodily by floo powder into or out of Hogwarts any time in the series, except for when the network was specially hooked up to allow students to return after Christmas break in HBP. Also, Harry's communiques with Sirius via floo powder began in GOF, and were specifically pre-arranged. It isn't beyond possibility that Sirius scheduled these meetings at times when Arthur Weasley or Kingsley Shacklebolt or somesuch other ministry official connected with Dumbledore and OOtP was positioned to ensure that the floo network was not as strictly policed as other times. There is extensive evidence to suggest that the floo network is generally closely watched, and so Death Eaters would not be desirous of using such an entry method, even providing there were no enchantments to prevent bodily traveling by floo powder into Hogwarts, thereby attracting attention not only to the assault on Hogwarts, but to their point of origin as well.

I think the most likely explanation, considering all the other magical enchantments preventing people from flying or apparating into Hogwarts, is that travel into Hogwarts by floo powder has always been prohibited, except perhaps by high-level school officials, but that communicating by floo powder was always allowed. We know that Umbridge shut this latter feature down in OOP in all but her own fire, and it is reasonable to assume that the Ministry shut down all floo access to Hogwarts after they finally acknowledged Voldemort's return at the end of OOP, except of course when they specially hooked it back up for students to return after Christmas in HBP.

I think this explanation dispenses with any need to attribute any praeternatural precognition to Dumbledore, though as I said, I'm not sure no one else has ever flooed into the school. If I missed someone, the whole thing falls apart.

-Q

[The Wrath]

I'm trying to reread them all before the 7th one comes out, and I've just thought of 2 more things that bug me.

Assuming that Tom Riddle's diary is a Horcrux, how did he preserve his 16-year-old self in it? He hadn't killed anyone yet, unless Myrtle being killed by the basilisk counts.

Secondly...when there's all these grandiose fights between wizards, such as the one at the end of book 5...why don't they all just cast the killing curse at each other? When Voldy was dueling Dumbledore in the Ministry of Magic, they were both just kinda dancing around using non-lethal spells. That seems dumb, given that they could kill each other with a single spell.

[non-contradictor]

Assuming that Tom Riddle's diary is a Horcrux, how did he preserve his 16-year-old self in it? He hadn't killed anyone yet, unless Myrtle being killed by the basilisk counts.

Secondly...when there's all these grandiose fights between wizards, such as the one at the end of book 5...why don't they all just cast the killing curse at each other? When Voldy was dueling Dumbledore in the Ministry of Magic, they were both just kinda dancing around using non-lethal spells. That seems dumb, given that they could kill each other with a single spell.

1. Riddle killed the Gaunts before he opened the chamber. He used their murder(s) to make the diary. He was 16 at the time.

source: http://www.hp-lexicon.org/timelines/timeline.php

2. Dumbledore can't kill Voldemort, and I'm pretty sure that Voldemort did try to hit Dumbledore with Avada Kedavra. Also remember that the unfogivables are Dark Arts, which Dumbledore probably wouldn't use on principle, same goes for the rest of the Order. I also gather that Avada Kedavra in particular is pretty difficult to cast, and is therefore not extremely practical for firing off quickly. It's also possible that some people can't bring up enough hatred to cast it effectively. Remember Harry's failed cruciatus? There's a lot of speculation on whether or not Harry would be able to use Avada Kedavra to kill Voldemort, even if he wanted to.

[Whoisjohngalt]

I'm trying to reread them all before the 7th one comes out.

Me too!

Secondly...when there's all these grandiose fights between wizards, such as the one at the end of book 5...why don't they all just cast the killing curse at each other? When Voldy was dueling Dumbledore in the Ministry of Magic, they were both just kinda dancing around using non-lethal spells. That seems dumb, given that they could kill each other with a single spell

Voldy actually taunts Dumbledore in OotP during the fight that Dumbledore wouldn't use a killing curse against him. So Dumbledore might actually have been holding the curse back knowing Harry had to kill Voldy in the end. Voldy actually uses the killing curse against Dumbledore and he is saved by the Ministry of Magic statues. (I remember in detail as I just finished the book)