Ubuntu 13.04 was a bumpy upgrade for NVidia
I have a two year old Dell Precision 4100 with a i7-2760QM CPU @ 2.40GHz, 16g (expandable to 32g), NVIDIA Corporation GF106GLM [Quadro 2000M], an 128g SSD and a supplementary regular hard drive. I keep it docked with a 30" monitor connected.
I've upgraded it through a few releases of Ubuntu. Most recently I upgraded to 12.10, which was a very smooth upgrade. A week or two later (today), I decided to upgrade to 13.04. That was less smooth.
Upon the first reboot I froze on a text-mode screen. I hit the power button and rebooted again. This time, I got a normal graphical login. Upon login I got my usual background but no launch bar or window manager.
I hit CTRL-ALT-F1 to get a text prompt and typed: "export DISPLAY=:0.0" so that I could launch things into the graphical environment (X-Windows). Then I typed "xhost +local:" which, in short, authorized all local terminals to do use the X instance. Next, not wanting to switch back and forth I typed "gnome-terminal". This gave me a terminal window on the desktop. I hit CTRL-ALT-F7 to return to the graphical environment.
I tried typing "unity" in the terminal but nothing happened. I went log hunting but dmesg said nothing and neither did anything in /var/log including /var/log/syslog and /var/log/X.org.1.log or any of their friends. So I tried running unity --log=./unity.log --debug in hopes that I'd get a reasonable log file. Instead, everything mysteriously came up!
I tried clicking on the software updater icon on the task bar. Confusingly it has changed icons to an A with a circle drawn with arrows around it. It claimed I lacked the permissions necessary and proper to perform this activity. So I clicked on the gnome-terminal window and hit CTRL-SHIFT-T and got a second tab. In there I typed gksu software-updater and it seemed to work. It claimed the update available was an nvidia-settings tool. That sounded like fun but the update didn't appear to do anything.
Next I went to the settings button of software-updater and clicked on the "Additional Drivers" tab. I noticed that the bottom radio button was checked with "nvidia-304" and that the top button was nvidia-310. That driver claimed to not only be newer but tested. I checked that and hit apply changes. Upon reboot everything came up cleanly.
So if you're planning to upgrade to 13.04, you may want to plan some extra time if you're on an nvida card especially if using the proprietary driver so that Civilization IV will run under Wine ;)
While the upgrade was bumpy, assuming everything works for the next few days I will consider it completely worth it. Ever since the first upgrade to unity, tabs on the Chromium browser haven't been reorderable. Any attempt resulted in a ripped tab (meaning a new window). This was ONLY on my laptop, the same releases worked fine on every other machine in the office or that I own. However, after this upgrade I can reorder tabs again! That alone is worth it for me. That was really the only problem I've had in years with Ubuntu on my laptop.