404 forbidden when trying to edit certain Pages

All the problems seem to happen at once. I was hacked yesterday and experienced an assortment of problems getting everything back up again.

Now, everything works, except for something very strange.
I have a lot of created Pages. Yet when I try to edit a lot of these pages, I get a 404 forbidden message when I click “save” or “save and continue editing. The pages work fine when I view them, I just cannot edit them.

I can, however, create a new page.

So I decided to just recreate all the pages. So I copy and paste the material from one page into a new page, and…IT DOESN’T WORK!

So I concluded there must be something wrong with the content of the page.
This particular page was just a page with 6 links on it. I narrowed it down to two links that made the whole page not work:

<a href="/excerpts-from-2003-2005">Selected Journal Entries from 2003-2005</a>
<a href="popUp('https://little-hypotenuse.com/quiz.html')">Quizzes</a>

If I just delete these links, the creating/editing of the post works.

And the same thing happens for a million other pages! One page in particular is just an essay. Nothing more. I haven’t narrowed it down to the problem area yet.

All of these pages worked two days ago before I got hacked, and before I recreated the site!

I remember having a similar problem with greymatter once (it wouldn’t post certain portions of an entry)…which was my stimulus to move to WordPress.

Please help, I have nowhere else to go!

my website: https://little-hypotenuse.com