File corruption with Word 2003 related to USB drive problems?

My roommate was using Word 2003 on my new computer with Vista. She had some
Word files that got corrupted. The error message said something about the
USB drive, as an explanation for why the files were corrupted. Apparently
she was saving her document on both the hard drive of the computer, and her
USB drive. But the files were corrupted on both the USB drive and the hard
drive, and she could not recover her data. This also happened once she got
her own computer a couple weeks later (which also has Vista and Word 2003).
It was the same error message (same USB drive too).

This hasn't happened to me yet, but I'm very worried. I have noticed that
when I try to eject my USB drive (a different USB drive) using the icon in
the lower right corner of the screen, the computer tells me it's safe to
remove the drive, but the green light does not turn off. It seems that many
people have observed this, and that removing the USB drive anyway does not
necessarily corrupt the data. But since I know that data corruption has
occurred in the past, I'm afraid to try it, so I've been turning off the
computer to remove the drive.

From my reading of various internet forums, it seems that there are file
corruption problems with Vista, and there are also USB drive problems with
Vista. I'm wondering if the two are related, and if the weird behavior of my
drive (green light not going off) is related to the file corruption that my
roommate observed. And if anyone else has had similar problems.

And if there's a fix.

I'm afraid to use Word while the USB drive is in the computer.