An update on the post count problem:
One of the vBulletin techies logged into the boards as an admin and to the server and could determine nothing wrong in the vB or server settings that was causing the problem. His suggestion is to upgrade to 3.0.7 (we are not on 3.0.3) and see if that helps at all. My gut feeling is that it won't, since most of the mini-upgrades were for security holes. I'm planning to make the upgrade this weekend if I get time, and we'll take a look from there.
I did, however, notice one other thing that's started to click over the last couple of weeks. Some forums have the option to "moderate posts" on, which means that before posts go public, they're put into a moderation queue and wait approval by the moderator. We had a usergroup issue recently that was causing a few members posts to always go into the queue, even though the forum didn't have that option turned on.
When I looked in the moderator queue, there were probably posts from 50 WFW threads stretching back for a long, long time. I cleared them all out, after making sure that they had already appeared on the boards. I went back into the mod queue today and saw four or five WFW posts in this forum that were appearing, including the back-and-forth replies from Levinson and myself and a couple of others. I deleted the 'queue' versions of these posts, and it appears that the reply counts for those threads is corrected (while some of the counts for older threads are still off).
So.... long story even longer: here's my suggestion. The next time you have a post that doesn't 'bump' and show up in the thread count, please PM and/or e-mail Paul and myself. We'll go into the mod queue and see if the post appears there, then test what effect 'accepting' or 'deleting' the post in the queue has to the reply count. If it appears that that is what's causing the count problems, then at least I'll have a more detailed version of the bug that I can contact the vB staff with.
Hope that helps.
-C