As of yesterday (while still on 2.6.4) I found that while trying to write a new post, the page redirects to the following page:
I notice (before the page redirects itself) that there seems to be an issue with the categories section:
For some reason, it tries to load the whole page within the 'categories' section. I'm guessing that this has something to do with the redirecting problem.
The problems only started this week, and I've upgraded to 2.6.5 today but the problem still exists. Does anyone know what might be causing the errors?