New page won't publish, just loads and loads

This week I created a new page that is a near duplicate of one of my existing pages and will eventually replace it. I noticed a problem when I tried to paste the content into the editor and it wouldn’t publish. When I clicked Publish or Preview, the bar at the bottom of the browser (don’t know what it’s called) would say “Sending request to sunriseonilion.wordpress.com…” and the wheel spins and spins and nothing happens. I’ve tried leaving it to sit for a long time and still nothing. I can save draft but I can’t update, publish, or preview.

So I thought I’d cut the content in half since it’s very image heavy and may be overburdening the servers. It worked. Then I tried to paste the other half and again, it wouldn’t publish. So I cut that in half and it worked. Then I repeated the process until I had just the last paragraph to add. By now I was adding half a sentence at a time until I could add no more. It’s like Zeno’s race paradox.

The problem seems to be unique to new pages. I can edit old pages just fine. Also, I can update the page without issue from my work computer. I am running the latest Firefox on Windows Vista. The website uses the 2010 theme. The update is more likely to fail if I’ve pasted lots of text or images.

My website is sunriseonilion.wordpress.com unfortunately I can’t link to the trouble page because it is set to private and I can’t change it while it’s broken. The page is nearly identical to this one: https://sunriseonilion.wordpress.com/odyssey/ It has lots of images and text but only two links, and both are internal links. All images are hosted onsite.

I have tried clearing my computer’s cache and rebooting.
I have switched to 2014 theme to no avail.
I have no plugins to disable.
I have tried recreating the page with no success.
I would rather not clear my browser’s cache because it has a lot of important stuff on it.
Due to virus issues I can only run Firefox in vanilla mode with addons disabled at each startup.