幫幫忙!wp mu 的登入問題

如標題!安裝好後密碼也對!但就是不行!請問是什麼問題?請教各位大大!
Warning: Invalid argument supplied for foreach() in C:\AppServ\www\wordpress\wp-includes\capabilities.php on line 31

Warning: Cannot modify header information - headers already sent by (output started at C:\AppServ\www\wordpress\wp-includes\capabilities.php:31) in C:\AppServ\www\wordpress\wp-includes\pluggable.php on line 372

Warning: Cannot modify header information - headers already sent by (output started at C:\AppServ\www\wordpress\wp-includes\capabilities.php:31) in C:\AppServ\www\wordpress\wp-includes\pluggable.php on line 373

Warning: Cannot modify header information - headers already sent by (output started at C:\AppServ\www\wordpress\wp-includes\capabilities.php:31) in C:\AppServ\www\wordpress\wp-includes\pluggable.php on line 334