I have even downloaded a new fresh copy of the wordpress and uploaded. The problem remained the same.
I put some exit checks in wp-login.php form and found this error message:
[Sun Apr 17 13:20:36 2011] [warn-phpd] mmap cache can’t open MY-DIRECTORY-ADDRESS\blog\wp-login.php (pid 1948 th 1796).
Anybody can help?
Regards