This is probably intended functionality but it's annoying enough that it's worth mentioning. In order to open a "Post New Message" window you have to log in. If, however, you want to compose a reasonably lengthy post in the window there, the server can time you out and unlog you without altering the header or in any way signalling this to you.
Now that isn't, in itself, a problem, I suppose... unless you hit "Preview" (or I assume "Submit" too), whereupon you get bounced out to the front page of Planewalker and -- this is key -- having lost the post in question! Now it's recoverable (Firefox, e.g., will do this for free) by backing up, but -- and this is also key -- at no point during the process are you told that you've been logged out (since the front page doesn't indicate it, and since the posting page is being loaded out of the cache so it's using your "Logged In" header) so there's no way to realize that that's all that's happened.
[I ended up losing one lengthy post, and almost another, to this confusion.]
My suggested fix, incidentally, would be to provide some other functionality after a logged-out post, like a page saying: "You're not logged in; would you like to do so now?" and saving the post in a cache somewhere until that's resolved. It's simple enough to execute, I think, and doesn't seem like a particular security risk. YMMV, though 
Got it working on Edit Post now - hopefully. Let me know if this'll hold together for you, and if there are any other pages you can think of that could use a simular functionality.