an error occurred while mounting /tmp "Help Please"

Are you saying that you have Ubuntu installed inside Windows, but you are *separately* trying to install it alongside (or in place of) Windows by booting from the Ubuntu CD?

What are the other messages you see when you boot the CD? Is "an error occurred while mounting /tmp" the entire text of the error that you see?

What version of Ubuntu are you installing, and which specific CD are you using to install (i.e., what is the name of the .iso image file)?

Did you MD5 test the .iso image before you wrote it to the USB flash drive? (See https://help.ubuntu.com/community/HowToMD5SUM.) If not, please do that now. If that doesn't check out, you'll have to redownload the .iso image, MD5 test the new image, and (assuming the new one checks out) write it to the USB flash drive again.

Did you verify that the USB drive was written correctly and is readable by the machine on which you're installing? To do that, boot from it, and immediately when you see the person and keyboard icons at the bottom center of the screen, press Spacebar, select your language, and select "Check disc for defects". (It's OK that it's a USB flash drive rather than a CD/DVD disc.) If that doesn't check, you'll have to re-write the .iso image to the USB flash drive (and run this test on it again).

The same thing happens to me with the Xubuntu 13.10 ISO. I checked it's integrity from the UnetBootin text "splash screen", and it says that no errors were found. When I reboot, it then freezes a few seconds in to the blue GUI splash screen.
Image name is xubuntu-13.10-desktop-amd64.iso

Yes, "an error occurred while mounting /tmp" is the only error message. I then am given the choice of skipping the error or manually resolving it. If I choose "manual", then I'm dropped to an initramfs prompt.