I have a problem opening shared folders on Windows 7 PC's because a Password is requested when none exists.
After hours of trial and error I discovered that the last PC turned on could see all computers, but none could see that one.
I could not see a 3rd PC until I turned on a 4th, which then became a problem. I now turn on a spare PC last so the others can all see each other.
Hope a fix comes soon?
I don't recommend having no password on any account. This is a security risk. Even limited user accounts should have passwords. You can edit the local policy editor to turn off passwords, but it's not recommended.