This is basically caused by upgrading PHPto a new version like 5.4 when you had 5.2 before and an old version of Joomla. The only solution is to upgrade Joomla or downgrade PHP, both of which can be a pain.
Strict Standards: Non-static method JLoader::import() should not be called statically in /home/userdir/public_html/libraries/joomla/import.php on line 29
Strict Standards: Non-static method JLoader::register() should not be ca........
Basically it's usually because your Cpanel has new IPs and the old IPs it knows are no longer available/working/valid.
The solution is to change the site's IP but you may run into issues for various reasons. Here is what I encountered below.
It redirects there even though public_html is empty and doesn't have any index or htaccess redirect.
This issue happened after a CPanel migration, the site is bein........
PDOException: SQLSTATE  Access denied for user 'db_user'@'localhost' to database 'dbname' in lock_may_be_available() (line
167 of /home/user/public_html/includes/lock.inc).
The username and password were correct but some reason CPanel added the user with no permissions! Edit the user's permissions to include "All" from Cpanel or MySQL and that is the solution.........