I have a couple of WD and Maxtor USB drives, they work fine.
Have you tried plugging them back in since the install?
As several of us have stated repeatedly in this forum,
unplug *any* USB devices during install. Then plug them
back in after the install has finished. If you have a USB mouse
and/or keyboard, they should be fine. But, maybe not.
I really believe, Microsoft should tell users this before
the install begins. I've heard about so many installs getting
stuck or failing because of peripheral devices. They should
also warn users, "Regardless of what our crappy advisor tells
you- please uninstall any AVs, firewalls, spyware protection,
turn off system restore- *anything* that monitors shite."