Problem after upgrade from version 2.5.1 to upgraded to 2.6

Hello,

I am facing the same problem with wordpress after upgrade from version 2.5.1 to upgraded to 2.6 I am getting following error

Notice: Undefined index: edit_page_form in /home/username/public_html/wp-includes/plugin.php on line 583

Notice: Undefined offset: 10 in /home/username/public_html/wp-includes/plugin.php on line 583

Notice: Undefined index: admin_menu in /home/username/public_html/wp-includes/plugin.php on line 583

Give us proper solution for this I am having following configuration for domain hosted server Apache/1.3.41 with php 4.4.8

Any help will be much appreciate…..

Thanks