I have an Ubuntu 8.04 installed in my computer. And every time I typed my login and password, only a blank white screen and a mouse cursor would appear. Nothing would happen. I don't know if I did something wrong into the internal system. GRUB is working okay except the whole Ubuntu system.

I'm typing this via LiveCD (Ubuntu 8.04) right now. Any ideas?

It sounds like you are able to start X, but not able to run your display manager (Gnome by default in Ubuntu). We need to find out why Gnome isn't working.

The first thing to check is the log files. /var/log/Xorg.0.log may contain some error messages that would suggest what is going wrong.

If not, you could try running X interactively to make sure your logs are working. If you press ctrl+alt+f1 at the blank screen, you should get to a text-mode login. From there, you can run You should also be able to run other commands from the text terminal. This will start a terminal emulator on the running X sessios:
You can switch back to the GUI using alt+F7 (it may also be F8 or F9 depending on how many times X has been started).

You may also find that this works to start your Gnome desktop:

I had same problem, went through the usual actors Xauthority and permissions, but it was none of that, my $home dir was full. moved stuff around (cmdline) and it works again.

Thanks for all the help Linuxquestions.org!

i had the same problem and discovered that my graphic card was causing the problem. boot using fail safe and check your graphic card drivers.