This probably has to do with the software itself and not the server. I would recommend reinstalling it from scratch and taking note of the "errors" that happen because they may be causing the errors that you see now. Also, the Simple PHP blog has its own forum, so I recommend you start there for most effectiveness in your battle against these errors ;).
Allow me to link you:
Code:
http://forums.simplephpblog.com/
Also, if this doesn't work out for you, there are plentiful of other blog scripts such as Wordpress that work equally if not even better than the Simple PHP blog. You might want to take that into consideration also.