I am too facing same problem .Few days ago server, where this blog is hosted,was upgraded to PHP 5.4 .
I haven’t installed any plugins there but I am seeing some bunch of errors there .
I am neither able to login too .
Strict Standards: Redefining already defined constructor for class wpdb in /public_html/blog/wp-includes/wp-db.php on line 49
Deprecated: Assigning the return value of new by reference is deprecated in /public_html/blog/wp-includes/cache.php on line 36
Strict Standards: Redefining already defined constructor for class WP_Object_Cache in /public_html/blog/wp-includes/cache.php on line 403
Strict Standards: Declaration of Walker_Page::start_lvl() should be compatible with Walker::start_lvl($output) in /public_html/blog/wp-includes/classes.php on line 531
