Crap, usually when posts start showing up at the wrong times it means the database is about to become corrupt, seriously. It happened exactly like that on my site, luckily i had a backup and only lost 2 days of posts.

That may not be the case here but it certainly sounds like it. I have seen it happen on other sites the same way as well.

I hope this site is being backed up daily like every forum should be. If one of the admins on here has full admin rights, log into the admin panel, scroll to the bottom, click Maintenance, Database Backup, Backup database to a file on the server. That is not the optimal way to create a backup on a large forum but since no one here has server access that is the only choice you have.I would do it quick to be safe but if it crashes back it up from a good backup 2 days earlier. If there is a large amount of files in the public html folder that can cause it to corrupt, vbulletin is weird like that. if that is the case, clean out any unnecessary files and then reload the database and it will fix it.