Cannot login to admin blog, but for a while could on only one computer.

– On my computers I cannot login at all to edit the blog, using either Firefox or IE
– on my wife’ computer (it is her blog) she could login OK
– but then after a week, she couldn’t login on her computer either, with any browser.
– when she did login, she did not have to enter her login id or password – she was automatically started in editing her blog.
– we can view the blog OK, but cannot login to the adminstration of it

This is what “cannot login” looks like:
– I am trying to login in using blogname//wp-login.php
– Instead of the typical login screen with some images, it just gives a basic text screen, with 2 input spaces (login: and password) and an OK button. When I enter the login ID and password, then WordPress just removes them and shows the same screen again. And again and again.

This is what I’ve tried (after reading many forum questions about login problems):

– I cleared all my cookies and cache
– I renamed by plugins directory, to hide it
– I renamed my theme directory name, to hide it
– I tried the Sexygirlgeek’s wp-login fix (https://www.sexygirlgeek.com/share/wp-login.phps)
– I turned off my firewall
– I cannot check my .htaccess file b/c I don’t have access to it – it is owned by apache server and not me

Any other suggestions?
Thanks, Vilis