Why is Ubuntu sometimes ugly when I log in? [duplicate]

Solution 1:

It's possible that gnome-settings-daemon (which controls theming) crashes or fails to start on login. If you want to confirm this as the case, you can enable crash reporting and see if it crashes when you notice it. From there, you can send in your crash report so it will hopefully be fixed.

To do this, open /etc/default/apport and change "enabled=0" to "enabled=1". You'll want to open this file as root; in a terminal type sudo nano /etc/default/apport to accomplish this. Change the value, hit Ctrl-X to quit, and press Y to save. Reboot, and crash reporting will be running and you'll be able to send in the problem when it happens.