MediaWiki internal error.

Original exception: exception 'DBQueryError' with message 'A database error has occurred
Query: SELECT log_type,log_action,log_user,log_namespace,log_title,log_params,log_comment,log_id,log_deleted,log_timestamp,user_name,user_editcount FROM `logging` FORCE INDEX (page_time,user_time),`user` WHERE (log_type != 'suppress') AND log_namespace = '0' AND log_title = 'Elspeth_of_Morven' AND (user_id = log_user) ORDER BY log_timestamp DESC LIMIT 51
Function: IndexPager::reallyDoQuery (LogPager)
Error: 2002 Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (111) (localhost)
' in /usr/share/mediawiki1.7/includes/db/Database.php:606
Stack trace:
#0 /usr/share/mediawiki1.7/includes/db/Database.php(561): Database->reportQueryError('Can't connect t...', 2002, 'SELECT log_typ...', 'IndexPager::rea...', false)
#1 /usr/share/mediawiki1.7/includes/db/Database.php(969): Database->query('SELECT log_typ...', 'IndexPager::rea...')
#2 /usr/share/mediawiki1.7/includes/Pager.php(236): Database->select(Array, Array, Array, 'IndexPager::rea...', Array, Array)
#3 /usr/share/mediawiki1.7/includes/Pager.php(148): IndexPager->reallyDoQuery('', 51, false)
#4 /usr/share/mediawiki1.7/includes/Pager.php(253): IndexPager->doQuery()
#5 /usr/share/mediawiki1.7/includes/specials/SpecialLog.php(53): IndexPager->getBody()
#6 [internal function]: wfSpecialLog(NULL, Object(SpecialPage))
#7 /usr/share/mediawiki1.7/includes/SpecialPage.php(748): call_user_func('wfSpecialLog', NULL, Object(SpecialPage))
#8 /usr/share/mediawiki1.7/includes/SpecialPage.php(534): SpecialPage->execute(NULL)
#9 /usr/share/mediawiki1.7/includes/Wiki.php(224): SpecialPage::executePath(Object(Title))
#10 /usr/share/mediawiki1.7/includes/Wiki.php(55): MediaWiki->initializeSpecialCases(Object(Title), Object(OutputPage), Object(WebRequest))
#11 /var/lib/mediawiki1.7/index.php(93): MediaWiki->initialize(Object(Title), NULL, Object(OutputPage), Object(User), Object(WebRequest))
#12 {main}

Exception caught inside exception handler: exception 'DBUnexpectedError' with message 'Error in fetchObject(): Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (111) (localhost)' in /usr/share/mediawiki1.7/includes/db/Database.php:735
Stack trace:
#0 /usr/share/mediawiki1.7/includes/db/Database.php(2620): Database->fetchObject(false)
#1 /usr/share/mediawiki1.7/includes/LinkBatch.php(98): ResultWrapper->fetchObject()
#2 /usr/share/mediawiki1.7/includes/LinkBatch.php(78): LinkBatch->addResultToCache(Object(LinkCache), Object(ResultWrapper))
#3 /usr/share/mediawiki1.7/includes/LinkBatch.php(68): LinkBatch->executeInto(Object(LinkCache))
#4 /usr/share/mediawiki1.7/includes/Skin.php(208): LinkBatch->execute()
#5 /usr/share/mediawiki1.7/includes/Skin.php(184): Skin->preloadExistence()
#6 /usr/share/mediawiki1.7/includes/SkinTemplate.php(106): Skin->initPage(Object(OutputPage))
#7 /usr/share/mediawiki1.7/skins/MonoBook.php(24): SkinTemplate->initPage(Object(OutputPage))
#8 /usr/share/mediawiki1.7/includes/SkinTemplate.php(151): SkinMonoBook->initPage(Object(OutputPage))
#9 /usr/share/mediawiki1.7/includes/OutputPage.php(821): SkinTemplate->outputPage(Object(OutputPage))
#10 /usr/share/mediawiki1.7/includes/Exception.php(150): OutputPage->output()
#11 /usr/share/mediawiki1.7/includes/Exception.php(174): MWException->reportHTML()
#12 /usr/share/mediawiki1.7/includes/Exception.php(260): MWException->report()
#13 /usr/share/mediawiki1.7/includes/Exception.php(294): wfReportException(Object(DBQueryError))
#14 [internal function]: wfExceptionHandler(Object(DBQueryError))
#15 {main}