I slogged through the first 10 chapters, impatiently, and in a great deal of annoyance at the monumental stupidity, but this was the one that threw me completely out of the story, and I was never able to fight my way back into it.

The whole 180 reversal of; "Oh noes, Voldemort is back! Beware of him and the DEs!" To; "Oh noes, the Mudbloods are stealing our magic! Beware of the Mudbloods and Harry Potter!" in the space of less than 2 weeks is beyond incredible.