Intalling from USB: "Invalid access to FAT?"

[Zebrasectomy]

So I'm trying to re-install Ubuntu onto a laptop that does not have a CD drive, but after booting from a flash drive I get a message telling me:

"FAT: Filesystem pane (dev sdb1)
Invalid access to FAT
fat+get_cluster: invalid cluter chaing (I_pos 0)"

Any idea what is cause this?

Background:
I tried installing an audio program on my girlfriend's laptop, and noticed a message informing me that there were "updates' that needed to be installed. I started installing them, but then her battery died in the middle of it.
We turned it back on, but the laptop no longer connected to the internet. The next time we turned it on, it would only load up an orange screen and linger there, frozen. SO... not knowing Ubuntu at all (it came with the laptop as defult), we decided we would just re-install Ubuntu. But even that is proving to be an overly complicated task.

*Also: Is there a way we can save her old documents once we re-install Ubuntu? I heard mention of partitioning? How does one go about doing that?

[lindsay7]

Reformat the usb drive. You can go to the web site for Unetbootin and install Ubuntu to the usb. You should be able to boot from the use. You have to go into you bios (hit the Del key or F2 depending on the computer) and set the boot instruction to boot from the usb first. You can then install Ubuntu from there.

[Zebrasectomy]

I tired all of those things except formatting the USB, so I'll give that a try and see if that works.
Thanks.