Thread:Project:Support desk/Fatal error: Cannot instantiate abstract class Installer

This is the error I'm getting :

'''Fatal error: Cannot instantiate abstract class Installer in C:\inetpub\wwwroot\mediawiki\includes\installer\Installer.php on line 469 PHP Fatal error: Cannot instantiate abstract class Installer in C:\inetpub\wwwroot\mediawiki\includes\installer\Installer.php on line 469'''

Do someone know how to resolve this ?

I have MediaWiki / Php / IIS / Windows Vista.

Thanks.