Unity 2d vs 3d and launcher icon resizing

Question

I have a Ubuntu 12.04 image on a flash drive. When I boot from that, I'm able to resize the icons in my launcher, and windows snap to half the screen. I assume this means that I'm running ubuntu 3d.

I just upgraded from Ubuntu 11.04 up to 12.04 (not a fresh install). Running the Ubuntu 12.04 installed on my hard drive, I am not able to resize the icons in my launcher nor snap the windows to half the screen. This command seems to say I'm in Ubuntu 2d, even though I have tried logging out, and specifically logging in with the regular Ubuntu rather than Ubuntu-2d.

$ echo $DESKTOP_SESSION
ubuntu-2d

How do I get the Ubuntu installation I have on my hard drive to act like the one I ran from the flash drive?

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Update: Here is the output of the debugging commands, as requested.

$ cat /var/log/Xorg.0.log

Output in: http://pastebin.ubuntu.com/984475/

$ lspci -nn | grep VGA
2.0 VGA compatible controller [0300]: Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller [8086:0116] (rev 09)

$ /usr/lib/nux/unity_support_test -p
Xlib:  extension "GLX" missing on display ":0.0".
Error: GLX is not available on the system

If anyone needs anything else, let me know. I don't really know what is important for this issue.

Answer 1

Fixed it!

Following the instructions on this thread, http://ubuntuforums.org/showthread.php?t=1741783, I removed the nvidia-current and nvidia-settings packages.

sudo apt-get purge nvidia-*

Now I'm able to log into an Ubuntu-3d session. Once in an Ubuntu-3d session, I'm able to resize the dock, and snap windows to the sides of the screen.