그누4 오류문의 채택완료

게시판을 누르면 이런 오류가 나는데요

Warning: include_once(./_common.php) [http://www.birdfriend.kr/bbs/function.include-once">function.include-once]: failed to open stream: No such file or directory in /home/hosting_users/elf3580/www/bbs/board.php on line 2 Warning: include_once() [http://www.birdfriend.kr/bbs/function.include">function.include]: Failed opening './_common.php' for inclusion (include_path='.:/usr/local/php/lib/php') in /home/hosting_users/elf3580/www/bbs/board.php on line 2 Fatal error: Call to undefined function alert() in /home/hosting_users/elf3580/www/bbs/board.php on line 9

로그인과 게시판에 문제가 있는것같은데 갑자기 오류가생겨서요 그누보드를 다시 깔면 해결되는지 알려주세욤~