Sometimes can't post, says I'm not logged in

This keeps happening regardless of the browser I’m using (but the OS is always Mac). I log in, hit reply, type my post, then when I try to submit or preview, it says I’m not logged in. If I then log back in, it continues to the preview page, but then loads a blank screen. Sometimes I lose the post.

Interestingly, when it says I’m not logged in, I can hit the back button and in the corner of the message typey box it says “logged in as…” like usual.

If you start typing apost, is there a time limit?

Or am I being punished for leaving in a huff and coming back? ::snugs down tinfoil hat::

Do you have “keep me logged in” checked? Otherwise it unlogs you after 15 minutes or so.