zeigt Dir Dein Editor keine Syntaxfehler an?
$res_content = $GLOBALS['TYPO3_DB']->exec_SELECTquery('t.uid, t.title, t.crdate, t.author, f.uid',
'tt_news AS t, fe_users AS f, tx_cwtcommunity_buddylist AS C',
't.deleted=0 AND t.hidden=0 AND t.author = f.username and c.fe_users_uid ='.$TSFE->fe_users->user['uid'].' and c.buddy_uid = f.uid',
'',
't.crdate DESC Limit 20');