I have a user who cannot log in from their computer. I can log in fine using their username and password. I suspect that there is a problem with either their machine or their network/firewall/something settings. Other users are logging in just fine.
I created a brand new account for this person manually (as I had created all 250 user accounts by automated means) just to be sure we were on the same page.
The user says:
I enter the username and password on the first log-in page [I put a log-in box on sites main page], I get a second log-in box [the regular wordpress log-in page] that says "Word Press - Microsoft Internet Explorer" that asks for a username and password, I re-enter it, and the "Word Press" box re-appears asking again for a username and password.