When you customized your Ubuntu desktop to replace the brown theme, you may have overlooked the login window. GNOME’s login window, called GDM (GNOME Display Manager), can be easily customized by installing themes.

Fedora is one of very few distributions that does not have the auto-login feature in its graphical user management tool. Auto-login allows the system to automatically login a user without requesting authentication, that is, it enables password-less logins. While it is a very convenient feature, it is a security risk. Why?

Reseting Gnome Settings

If your gnome-panel corrupt , Application Menu, Places Menu and System Menu and some other menu items will disappear.
How to recover it

Boot the system upto Login Window. Press Ctrl + Alt+F1

Now You will get a Text based login screen

login with your username and password

now you will get a $ prompt.

I think this should work for any Linux operating system using Gnome, I have tested on Debian and Ubuntu.

Well, automatic login will let you avoid to enter your login and password each time you turn on your PC, this could be insecure, but if your computer is physically secured it is Ok to enable this, that could make your booting more smooth.

How to do it?

Ubuntu makes it easy to enable automatic login if you're using a login manager such as GDM. I was recently setting up a minimal Ubuntu 9.10 system with an LXDE desktop and no GDM. Here's how I enabled automatic login.

Ubuntu Tweak 0.5.4 was released today. It doesn't come with new major features except an option to customize the GDM (login screen), which you can use to change the login screen background, logo, disable the user list, disable the login sound and disable showing the restart buttons:

How to achieve a more unified login experience using KDE SC by modifying the KDM Login Screen and the KSplash screen to match your needs.

By default, Ubuntu requires that you login each time you run the operating system. If you are the only person using the computer and aren’t worried about security you can enable automatic login.

You can use an on online attack as an opportunity to check that your security systems detect when a server is being bombarded with unsuccessful login attempts, and that individual accounts lock after a small number of unsuccessful login attempts.