Had Joomla running on our IIS 6 box fine, but needed to install something that required .NET 4 on the same server today.

Now Joomla is working, but i have to specify the exact URL for everything now, so where as www.schoolsite.com/administrator use to bring up the back end administrator i now get what look like asp errors like "Server Error in '/' Application." But if i specifiy www.schoolsite.com/administrator/index.php it loads.

The default document in IIS is set to index.php, if i disable .net support i get page cannot be displayed when trying /administrator without specifiying index.php.

So why has IIS stopped looking for and loading index.php when specifiying just the folder?