I've been trying all day to create a new post for my blog. I was running V3.0 (I use the Mimbo Pro theme, and the Dispatch child theme). Every time I tried to either save a draft or publish a post the browser inexplicably went to my blog's Error 404 Page Not Found page.
I tried deactivating all plugins, and that didn't help. So, I upgraded to V3.0.1.
Now, I'm having the same problem, plugins activated or not.
Can somebody please help? I've found no support threads about this anywhere, and I have no idea what to do about it.