You have to be root to be able to delete it. In CuteExplorer enable the option for root access, reboot and delete the file (carefully!), then disable this option to avoid any future problems. You can also do it manually with xterm (you need to have tootsh installed): Code: sudo gainroot rm /etc/systemui/OptimizeN900.xml
sudo gainroot rm /etc/systemui/OptimizeN900.xml