This one is on my last nerve.

1) Click on post.

2) Think about writing up a response.

3) Go do something.

4) Wait ten minutes.

5) Write up a response and hit "submit."

6) "Unknown or expired link."

7) roll back, roll forward, and hope you can ctrl-c what you wrote rather than have it vanish into the aether.

8) refresh link.

9) ctrl v if you're lucky.

10) make the comment you wanted to make in step (5).

If you're going to time it out, could you write what I wrote into cache and give me a place to resubmit? I'm sure it has something to do with your structure changing when there's a comment, but it's like playing raquetball in a minefield.