I had the same problem, John, and finally solved it by changing from a "threaded" display to a strict chronological display. You no longer see the relationship between postings and replies, but the subject is still diplayed.

What you see are all the newest messages at the top in blue (or whatever color you have chosed for your browser setup) if you haven't read them. The remaining 500 messages are still there, but are just in a list below the new messages.