NOTE: The above post finally made it through after about eight attempts. While this may be browser-specific, the error message suggests a server-side configuration problem.
It's also worth considering that for every member who has this problem, only a fraction will probably succeed or try to succeed in getting a post through after several failed attempts.
So I REALLY recommend checking the server logs.
Really.
Edit: By "above" I mean my previous post on Page 1, not the previous "irony" posts that are probably a result of several queued attempts to post -- and ironically so, indeed. ;-)