Fixes #27.  When the default controller was used, the _detect_uri() method was returning an incorrect URI, which caused a 404 when a query string was used and no controller specified. via Dan Horrigan
diff --git a/system/core/URI.php b/system/core/URI.php
index 1b479e9..c43cde0 100644
--- a/system/core/URI.php
+++ b/system/core/URI.php
@@ -173,6 +173,12 @@
 			$_SERVER['QUERY_STRING'] = '';
 			$_GET = array();
 		}
+		
+		if ($uri == '/' || empty($uri))
+		{
+			return '/';
+		}
+				
 		$uri = parse_url($uri, PHP_URL_PATH);
 
 		// Do some final cleaning of the URI and return it