Ubuntu – How to solve problem related to black screen with cursor only after loging in


Suddenly, I got crash report after logging in to my primary account. It says "cannot open display". But, everything work just fine while loging in with "Guest" account. I tried using these methods which didn't work for me:


After getting that black screen I pressed ctrl + alt + f1 key, then after loging in with primary username. I started typing these command:

sudo apt-get install ppa-purge
ppa-purge ppa:unity-team/staging
sudo apt-get update
sudo apt-get intall --reinstall ubuntu-desktop
sudo apt-get install unity


cp .config/dconf/user .config/dconf/user.bkp
rm .config/compiz-1/compizconfig/config .config/dconf/user

sudo apt-get install dconf-tools
rm .config/comp-2-1/compiz config/config; dconf reset -f /org/compiz/

Any solutions?

Best Answer

I fumbled around with Nvidia drivers and this black screen issue for two days. And I fell into this pit because of the 14.04 upgrade from 12.04. Grrr!

The original issue I was trying to resolve was the high cpu utilization of firefox, compiz & Xorg which made the graphics fairly unusable. After attempting to resolve that issue by upgrading the Nvidia driver, all went south and the black screen of death ensued.

Here's some commands that speak to my desktop configuration in case that helps...

"lshw" command produces:

description: Mini Tower Computer
product: OptiPlex GX270

"lspci -vnn | grep -i VGA -A 12" command produces:

VGA compatible controller [0300]: NVIDIA Corporation NV18 [GeForce4 MX 440 AGP 8x]

"wmctrl -m" command produces:

Name: Metacity
Class: N/A
Window manager's "showing the desktop" mode: N/A

At the end of the day, I'm not 100% sure what worked as I fumbled around so much. Here's what I think did it.

Use the following to get rid of all Nvidia bits and rely on the default driver Nouveau.

sudo apt-get purge "nvidia *"

Then opt for using Metacity instead of Compiz. Those are the two salient changes I made and the result is a much improved graphics experience with acceptable cpu utilization when doing something such as video streaming from CNNx. Firefox still shows high cpu utilization in "nice top" but that doesn't seem to impact the graphics and especially the video streaming.

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