Good call - completely forgot about running a chkdsk.
@OP: Before doing any of the previous suggested steps, try this... From the Install screen after booting off of the USB drive, instead of clicking "Install now" there should be a link in the bottom left corner that says something like "recovery". Click that, and then click on the "Command Prompt" option.
In the command prompt window type in:
chkdsk c: /f /r
let it run, and then try to install again. If it does not work and you get the same error, continue with the steps I posted previously.