Is my installation faulty? Posts don’t publish on time, site map wont update etc

I have a blog that ever since late version 2.7 will not publish posts on the same time schedule.

Each time a new WordPress version comes out I hope that I can schedule posts to publish at a later date, yet it never works. So I did find a plugin called Scheduled MIA’s which I’m currently using, but I find it funny that I need to use a plugin for functionality that should be working in the first place.

Anyway, the other issue is that my Google Sitemaps plugin does not appear to auto update the site map like it does on my other blogs.

Please keep in mind I have 3 other blogs installed on the same server with nearly the exact same plugins yet I can schedule posts to publish at a later date (and it works) and my Google Sitemap is autoupdated there as well.

What do you suggest I do? I assume there is an issue with my first blog but I can’t figure it out ?? I just want it to work like the others do.