Plötzlicher Fehler: CookieSessionFactory.class.php ?!?

Information: 
error message: PHP notice in file /homepages/7/d24605729/htdocs/mb/wbb/wcf/lib/system/session/CookieSessionFactory.class.php (149): Use of undefined constant COOKIE_PREFIX - assumed 'COOKIE_PREFIX' 
error code: 0 
file: /homepages/7/d24605729/htdocs/mb/wbb/wcf/lib/system/WCF.class.php (281) 
php version: 5.2.17 
wcf version: 1.1.9 (Tempest) 
date: Tue, 12 Nov 2013 15:11:51 +0000 
request: / 
referer: 
Stacktrace:#0 /homepages/7/d24605729/htdocs/mb/wbb/wcf/lib/system/session/CookieSessionFactory.class.php(149): WCF::handleError(8, 'Use of undefine...', '/homepages/7/d2...', 149, Array) 
#1 /homepages/7/d24605729/htdocs/mb/wbb/wcf/lib/system/session/SessionFactory.class.php(63): CookieSessionFactory->readSessionID() 
#2 /homepages/7/d24605729/htdocs/mb/wbb/lib/system/WBBCore.class.php(200): SessionFactory->get() 
#3 /homepages/7/d24605729/htdocs/mb/wbb/wcf/lib/system/WCF.class.php(98): WBBCore->initSession() 
#4 /homepages/7/d24605729/htdocs/mb/wbb/global.php(18): WCF->__construct() 
#5 /homepages/7/d24605729/htdocs/mb/wbb/index.php(7): require_once('/homepages/7/d2...') 
#6 {main}

Fatal error: Connecting to MySQL server '' failed.


 
You get more information about the problem in our knowledge base: http://www.woltlab.com/help/?code=2002
Information:
error message: Connecting to MySQL server '' failed.
error code: 2002
sql type: MySQLDatabase
sql error: Can't connect to local MySQL server through socket '/tmp/mysqld.sock' (2)
sql error number: 2002
sql version: 
file: /homepages/7/d24605729/htdocs/mb/wbb/wcf/lib/system/database/MySQLDatabase.class.php (31)
php version: 5.2.17
wcf version: 1.1.9 (Tempest)
date: Thu, 14 Nov 2013 10:34:08 +0000
request: /
referer: 


Stacktrace:#0 /homepages/7/d24605729/htdocs/mb/wbb/wcf/lib/system/database/Database.class.php(78): MySQLDatabase->connect()
#1 /homepages/7/d24605729/htdocs/mb/wbb/wcf/lib/system/WCF.class.php(296): Database->__construct(...)
#2 /homepages/7/d24605729/htdocs/mb/wbb/wcf/lib/system/WCF.class.php(95): WCF->initDB()
#3 /homepages/7/d24605729/htdocs/mb/wbb/global.php(18): WCF->__construct()
#4 /homepages/7/d24605729/htdocs/mb/wbb/index.php(7): require_once('/homepages/7/d2...')
#5 {main}