Hi. I don't know why this happens, but it's very strange.
After entering my username & signature, Ubuntu usually shows the GNOME desktop. But this time it's only showing blank, light brown color of screen, and after 10-15 seconds the quarter top left of the screen displays white box, but GNOME doesn't appear. I've tried Failsafe GNOME but the problem still appeared. What can I do now?

(I type this using flwm window manager)