SL6.1 USB install fatal error

[Advrk Aplmrkt]

I managed to boot into the text installer (still can't get GUI because
of this: http://scientificlinuxforum.org/index.php?showtopic=453) for
SL 6.1, and went through every step till I specify "use entire disk"
during install and start the installation process.

At this point, I would see messages saying the installer is
partitioning the hard disk, copying files, etc., then always the same
error:

"An error occurred mounting device /dev/sdb1 as /boot/efi: mount
failed: (9, None). This is a fatal error and the install cannot
continue."

Here is a screen shot via my phone:

http://www.imagebam.com/image/0bd326143256204][IMG]http://thumbnails39.imagebam.com/14326/0bd326143256204.jpg

I have tried to boot via USB the LiveCD, LiveMiniCD, and LiveDVD
images, same result.

Note: /dev/sda is my hard disk, and my USB drive is apparently mounted
in /dev/sdb

Does anyone know what this means and how I can resolve the issue?
Thanks so much.