Software updater window only showing title bar

I m getting it too !

I too am seeing this on my machine:
ram: 11.7 GiB
processor: Intel® Xeon(R) CPU W3520 @ 2.67GHz × 8
video: Gallium 0.4 on AMD RV730
OS: 64-bit - Ubuntu 14.04.1 LTS

Status changed to 'Confirmed' because the bug affects multiple users.

Screenshot

I am suffering from this as of today using xUbuntu 14.04 updated to most current. It did start when I got a 404 on a repo but was able to exit and remove it and when I went back in I think the last thing I did was actually tell the GUI to not run a reload of source files after it came back with update catalog out of date after I adjusted the repo list (I wanted to run terminal apt-get update and watch for issues. After I told it not to and hit exit then when I tried to open the gui again it gives me titlebar only.

Now I am able to run apt-get upgrade and it ran through everything just fine.

But now any time I try to open Software Upgrade from the system control panel area I get title bar only.

I have not restarted yet I have to wait until I am physically with the machine later for that, but it isn't looking good, glad I don't mind using terminal commands.

Ok, it did not even require a full system restart. I was able to ssh in to my box (and close out VNC client) and then all I did was restart my GUI (for xUbuntu 14.04 trusty is LightDM (kicks Unity's ass by the way I swear by xUbuntu and will not use Ubntu and Unity (just a side note anyways back to it). From SSH session all I did was issue sudo service lgihtdm restart and viola after it restarted and I logged back in Software Updater GUI is opening as it should again.

Keep in mind if you go to try this you CAN NOT do it from your desktop with a terminal emulator. If you do not use SSH then you can hit I think it's the ctrl+alt+F keys (ie F1 - F8) it could be just ctrl+F key and that should drop you to a text only login screen. From there just login with your user and password and when you get the $ prompt then just use:

sudo service lightdm restart

(or you could prolly fill in whatever it maybe that runs unity).

If you have xUbuntu the Lightdm restart will work for you, you can stop here, below is further info on restarting Unity for those with Ubuntu...

Now I have googled around and found the following.. Ubuntu itself looks like sudo service lightdm restart may work. If not try one of the following:
After getting past text only login:

killall unity-panel-service

and if it does not restart on it's own to start it run:

/usr/lib/unity/unity-panel-service

If it's the 2d version you are running then use:

killall unity-2d-panel

Some have said in 14.04 that the above unity-panel stuff may not work, but the following does:

kill -9 $(pgrep unity-panel-ser); compiz --replace

Sources:
http://askubuntu.com/questions/495997/how-to-properly-restart-unity
http://askubuntu.com/questions/46788/is-it-possible-to-restart-the-unity-panel-without-restarting-compiz
http://askubuntu.com/questions/371915/how-to-restart-unity-panel-service

Sorry if you use the Ctrl+alt+F key you will need to use
ctrl+alt+F7
to get back to your X Server Console.

Again it may actually be Ctrl+Alt+F7 OR Alt+F7 OR Ctrl+Alt+F8 OR Alt+F8 it just depends on what exact version you are using of Ubuntu as to how you will accomplish this.

Source:
http://askubuntu.com/questions/157617/reverting-from-ctrl-alt-f1

Sorry about not adding this to my last comment, but wanted to make sure I provided the info for how to get back to your standard X Server console :-) .

If all else fails you can issue:

sudo shutdown -r now

From any console and this will cause your system to do a proper restart right away with NO wait. Once restarted your machine should return you back to your default X Server console should you lose your way.

Hi.

I couldn't fix it rebooting, so I upgraded to 14.10 and it was fixed. Upgrading later to 15.04 keeps it working too.
There should be another fix better though.