Strict Standards: call_user_func_array() expects parameter 1 to be a valid callback, non-static method GoogleSitemapGeneratorLoader::Enable() should not be called statically in /wp-includes/plugin.php on line 403
try this:
1. open file /wp-content/plugins/google-sitemap-generator/sitemap.php
2. find line: function Enable() {
3. replace this line with: public static function Enable() {
