Here's some thoughts:
1. Can you rename files on this drive. I had a similar problem where the drive name wouldn't show and I noticed that my files were read only. So I wrote a script to fix it, it's attached in case it fixes your issue.
2. Take a look at this posts
that shows a possible problem with portable apps if that is installed on your USB
3. Can you rename them through the disk management module?
4. Are you logged in with rights to rename drives?
5. Are the drives readable, I know that my USB's appear as Local Disk if they are corrupt.
And a couple of long-shots, worth while mentioning, but I expect you'll rule them right out.
1. Run chkdsk /R /X on them to check that they are sound
2. Ensure all drives are de fragmented so that windows resources are clear.