A few more data points. I deleted the cookies in Firefox this morning. The forum had me log in and show new post worked.
This evening, I tried again, still have to log in but show new post not working. For giggles I logged in on my work laptop, running IE 8, which I do not use as a rule to visit this or other forums. The same, no new post. I log out go back to my home (Firefox) comp to post this, and show new post brings up a few from today and a couple from months ago which I may have not read. This without making any changes. My i pad and Samsung tablet work fine.
I don't have any trouble when I visit other forums that run "Simple Machine"...John