In the search archive of this newsgroup Maurice Joseph (http://thread.gmane.org/gmane.org.wikimedia.mediawiki/7955/focus=7955) pointed to this error on the FAQ: http://meta.wikimedia.org/wiki/Talk:Installing_MediaWiki_on_Windows_Server_2...
Are you running a windows server ? This could be an information for further follow ups.
Hope this helps.
François