I followed these instructions: http://www.ubuntu.com/download/desktop/create-a-usb-stick-on-windows After that, I got to the 'installer boot menu', where it asks whether you want to boot off of the flash drive or install. I choose the option: Try Ubuntu without Installing It freezes on that screen.
2 Answers
I experienced the same problem, and it turns out I was using the 64 bit installer on an old laptop that only supported 32 bit. When using a DVD to install, it provided a helpful error, but the USB installer just froze.
That is od..I assume you are on Windows 8, try to boot to BIOS and disable System Protection. I have a feeling I experienced something similar when switching from Win8 to Ubuntu. Post back please, I'm wondering if my assumption was correct ;)
Best regards!