Unable to login

Sergey, hello! PHP's open_basedir function is a security measure that prevents files and scripts that are outside of the "home" directory from being opened. If the PHP open_basedir setting is enabled, then all file operations are limited to one folder on the server, preventing unauthorized users from accessing scripts. When a script tries to open a file that is outside the root directory, such as fopen() or gzopen(), the path to the file is checked. When a file is outside the allowed directory, PHP will refuse to execute it and an error will appear like:
Warning: file_exists() [function.file-exists]: open_basedir restriction in effect. File(/home/user_name/public_html/wp-content/uploads/2006/12/picture.jpg) is not within the allowed path(s): (/home/user_name:/usr/lib/php:/usr/local /lib/php:/tmp) in /home/user_name/public_html/wp-admin/inline-uploading.php on line 226 which is similar to your error.
To solve this problem, you need to contact your hosting