I figured it out. When the installation pops up, I clicked F6, then ESC. In the text that appeared on the screen, I changed quiet to noquiet, splash to nosplash, and added nomodeset right after nosplash.
This was very helpful and worked for me too
The install finally opened. When installed I checked "install updates during install" and "install third party software" (or something like that) after connected to my wireless network, and when the setup finished and I rebooted my computer, everything was working just fine, with NVidia drivers installed and Unity 3D working.
I didn't see those options, so after it installed it went back to the test drive.
For Alternate install: After base packages are installed (before grub install), open a prompt (ALT+F2) and "chroot /target", then "apt-get install nvidia-current", "CTRL+D" to exit chroot, "ALT+F1" to resume install. Complete the installation and you should be good to go.
Don't know, mine installed then I was back at the test drive and couldn't make permanent changes. Rebooting went to blank screen.
So at that point I rebooted and selected recovery mode and then chose fail safe graphics option. This allowed me to boot. Then I was able to go to Ubuntu Software Center and get nvidia current (wow, a lot of bad reviews). I also was able to run the updates (387 of them). I was able to reboot to 12.04 ok. Then I opened system settings, additional drivers, and searched. Current NVIDIA accelerated driver was activated. I activated post-release updates. Rebooted and all is good so far.