Comment 1 for bug 1178910

You are probably affected by this bug: https://bugs.launchpad.net/ubuntu/+source/ubiquity/+bug/1082458

The problem is that this got fixed in 13.04 (by removing the webcam feature) and backporting the installer seems not possible without messing around, so i would try to add the boot-parameter modprobe.blacklist=uvcvideo on the live boot medium. This should disable the webcam and prevent ubiquity from crashing.

To add the boot-parameter press any button if you see the "human = keyboard" icon at the bottom of the screen. You'll land at the boot menu with options like "Try without installing" etc. Now press F6 to enable boot-parameter editing and press Esc to close the menu that popups. Now you are able to edit the text at the bottom of the screen (above the options). Insert the text "modprobe.blacklist=uvcvideo" before the "--".
The text should look like this afterwards http://imgur.com/X6cBF81 (note the spaces before and after "http://imgur.com/X6cBF81").
Now press enter and proceed as usual with the installation.

I'll mark this bug as incomplete for now. Please reply if my solution worked that i can transfer this bug into a question on lp as bug-reports disappear.