[kh99]

I'm not sure offhand why there'd be a difference, but when you rebuild forum information it calls function build_forum_counters() (in includes/functions_databuild.php) for each forum. That function adds up the replycount fields for each thread where visible = 1 and open <> 10 (I can't remember what an open of 10 means). It also looks like it doesn't count posts by "global ignore" users. So it could be that for some reaosn you have "orphaned" posts that aren't counted in any thread, or threads that aren't in any forum. If you have the CMS, I think comments are posts, but I'm, not sure if they're in threads or forums.