Hmm... I'm wondering...
OK, so what I can gather, logically from the information you've provided is that StatPress visitors is experiencing a database error of some type, but when it tries to log that error it is unable to find core WordPress files.
My current guess is around file and directory permissions in the root WordPress directory '/home/xxxxx/public_html/' as the upgrade process was unable to delete .maintenance, it might well have been unable to delete wp-load.php and not upgraded the install properly (possibly the same for other files in that directory).
One option would be to edit wp-load.php and on the second line add something like:
/* This is a comment that I don't want to see */
And then go to the updates screen and tell WordPress to reinstall itelf and see if that text disappears from the file.