Error in the last installation of joomla1.5.23

I've got this error after I deleted the installation folder in c:\xamp\htdocs\joomla15. This is the error I got when I tried to open the administrator site to log-in to my back-end:

Strict Standards: Non-static method JLoader::register() should not be called statically in C:\xampp\htdocs\joomla15\libraries\loader.php on line 71

Strict Standards: Non-static method JLoader::import() should not be called statically in C:\xampp\htdocs\joomla15\libraries\joomla\import.php on line 32

Strict Standards: Non-static method JLoader::register() should not be called statically in C:\xampp\htdocs\joomla15\libraries\loader.php on line 71

Strict Standards: Non-static method JLoader::load() should not be called statically in C:\xampp\htdocs\joomla15\libraries\loader.php on line 161

Strict Standards: Non-static method JLoader::register()开发者_开发百科 should not be called statically in C:\xampp\htdocs\joomla15\libraries\loader.php on line 138

Strict Standards: Non-static method JRequest::clean() should not be called statically in C:\xampp\htdocs\joomla15\libraries\joomla\import.php on line 33

And so on. How do I solve this?

* EARLIER VALUE : var $error_reporting = ‘-1′;
* CHANGED VALUE: var $error_reporting = ’6135′;

Set this values in configuration.php file of Joomla