Index: includes/install.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/install.inc,v
retrieving revision 1.64
diff -u -r1.64 install.inc
--- includes/install.inc	21 Aug 2008 19:36:36 -0000	1.64
+++ includes/install.inc	21 Aug 2008 23:49:05 -0000
@@ -210,7 +210,7 @@
 
   foreach (scandir('./includes/database') as $driver) {
     $driver_dir = './includes/database/' . $driver;
-    if (!is_dir($driver_dir) || strpos($driver, '.') === 0) {
+    if (!is_dir($driver_dir) || strpos($driver, '.') === 0 || !is_file($driver_dir . '/database.inc')) {
       continue;
     }