I think there were actually two different problems that cropped up lately. One is people getting a "page not found" error when they try to post. The other is people getting logged out. I'm having trouble keeping them straight, so I'm making two different threads.
Please respond here if you're problem is "page not found" or "page cannot be displayed" or whatever it is. There'll be another thread in a moment for people getting logged out (and "session time out").