Thank you for posting this. I know of at least one other member having this problem so it's good (sort of) to know that others are encountering this.
What you are getting is the page someone with an IP address ban gets. However, since you're accessing the site in the first place, you obviously aren't blocked from it. Moreover, your IP addresses do not appear to be the types that would get blocked by anti-spamming measures.
Let me know if this is happening from more than one location if you can. That could help us figure out if it is an IP address problem, an account problem, a site problem, or something else. In the meantime, I'll contact Matt about this thread, as there are no measures I can think of that the elves can take to rectify this; the ideas I already asked the other member to try didn't work.
Suggestions from tech-oriented members are also very welcome here.
Earlier today I added a few pictures, and found that I could edit them. But I still couldn't edit a mountain page.
A bit later today I added an album, but to preempt any problems, I typed the text and specified the primary image all in one go. Then I tried to edit it, just to see if the object type might be part of the equation, but that worked fine too
So, I again tried to edit one of my mountain pages again, and now it works!
Whether the problem is solved or simply gone away until it reappears, I don't know, but for now it's all right again.