After looking at the posts on this issue and sending all the info to my host provider, they cannot solve the problem. They tried different solutions:
-Try to open location wp-admin/index.php It should work.
-Added index.php to the list of indexes>
Still not working but the login page this time redirects me to the same login page.
I am using WordPress on my PowerBook (Apache) and everything works fine.
They use Windows 2000 Advanced Server.