After logging in, there's a black screen and my cursor, nothing else! in Ubuntu 12.10

I've been using Ubuntu(12.10) for a long time, and recently, my Ubuntu went through yet another update.

The whole update prompt showed up, following by a password prompt, and finally the good ol' progress bar...

Everything went well, and later on, I shut down my computer.

The next day, I turned my PC on, went to the login screen. I went ahead, and logged in, but after that, all I could see was a black screen, and my cursor!

I checked the forums, and got various tips, none of which worked...

Now I'm stuck with an Ubuntu installation that's completely useless.

One more thing:

I even tried logging in through Guest, but same problem! :\

My Computer Specs:
Motherboard: Intel DG41WV
Processor: Intel Core 2 Quad Q6600 @ 2.40GHz
Graphics: Intel G41 Express Chipset
RAM: Dual Channel, DDR3 2*2GB (4096 MBytes)
HDD: Seagate 500GB SATA

---- DETAILED INFO ----

To be a little more precise about my problem, after I log in, I can see a black screen and my cursor. Plus, importantly, I was able to see a login screen, hence I'm sure Ubuntu is rendering properly, and also pretty sure that there's no problem with the drivers (Otherwise I shouldn't even get a login screen, right?).

Anywho, another (probably) important thing is that, after logging in, I can hit Ctrl+Alt+1 and get up a recovery console.

The only thing that doesn't load is my actual GUI desktop

Then, I ran unity from the recovery console, it went through a few commands, got stuck at OpenGL for a few seconds, then zoomed throught many more lines of code, and ended up with this:

ERROR 2012-01-03 20.51.23 unity.launcher.Icon TrashLauncherIcon.cpp:62 Could not create file monitor for trash url: Operation not supported

*** glibc detected *** compiz: malloc(): memory corruption: 0x09c861d6 ***

After that. back at Ctrl+Alt+F7: Desktop Background + Cursor

So back to the terminal again, I had to hit Ctrl+C to get back again.

now, I typed unity again, and this was the output:

WARNING: no DISPLAY variable set, setting it to :D
compiz (core) - Info: Loading plugin: core
compiz (core) - Info: Starting plugin: core
unity-panel-service: no process found

so now I did a sudo service lightdm restart :

X10: fatal IO error 4 (Interrupted system call) on X server ":0"
after 131 requests (130 known processed) with 0 events remaining.
lightdm stop/waiting
lightdm start/running, process 2852

Im back at the login screen, and I login again, now Im back to black screen (Yes, I lost the Desktop Background as well)

So, once again, I try unity (same response as last time):

WARNING: no DISPLAY variable set, setting it to :D
compiz (core) - Info: Loading plugin: core
compiz (core) - Info: Starting plugin: core
unity-panel-service: no process found

And still a black screen! :\

Just for completeness, this problem also occurs when you mistakenly installed the "nvidia-319-updates" package, but you do not have an nVidia graphics chip on your system. In my case this package was an indirect dependency from package "libopencv-dev".

So, when you're running on an ATI or Intel grpahics chip for example, and you installed openCV (package libopencv-dev), OpenGL gets broken and you'll get a black screen with mouse cursor after logging in. To resolve in this case, just remove nvidia's packages:

sudo apt-get remove nvidia-*

See this bug on launchpad for more details

I've successfully solved the problem. Well, what I did was this:

sudo apt-get install ppa-purge
sudo ppa-purge ppa:unity-team/staging

sudo apt-get update
sudo apt-get install --reinstall ubuntu-desktop
sudo apt-get install unity

That, followed by a reboot, is the recipe for a fix! :D

Maybe you need to reset compiz and Unity config files.

You can try a soft reset (only Unity/Compiz files, but I didn't test this): http://www.webupd8.org/2012/10/how-to-reset-compiz-and-unity-in-ubuntu.html

There's a hard reset: https://askubuntu.com/a/244064/123806

But it will erase config of some apps. Try it as a test user, go to tty1 (Ctrl+Alt+F1):

sudo adduser test

Return to tty7 (Ctrl+Alt+F7) and try login. If works, we confirm it's just a problem in your config file. Else follow the link above. (after tests, "sudo deluser test" and "sudo rm -Rf /home/test" will erase).

If Ctrl+Alt+T doesn't work...

First login and get blank screen, then Ctrl+Alt+F1, backup and remove your config file:

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

We need to remove both files at same time.

Ctrl+Alt+F7 and the expected is Unity will open.

I had same issue, but i noticed that after running

sudo apt-get remove nvidia-*

command, which did not changed anything (even after reboot)
there were some old unnecessary packages, and after removing them with command

sudo apt-get autoremove

and rebooting all was correct, desktop is loading as expected.