diff --git a/install.php b/install.php
index ed3f3266..6a65fcc6 100644
--- a/install.php
+++ b/install.php
@@ -536,6 +536,16 @@ Typecho_Cookie::set('__typecho_lang', $lang);
                                 }
 
                                 if($success) {
+                                    // 重置原有数据库状态
+                                    if (isset($installDb)) {
+                                        try {
+                                            $installDb->query($installDb->update('table.options')
+                                                ->rows(array('value' => 0))->where('name = ?', 'installed'));
+                                        } catch (Exception $e) {
+                                            // do nothing
+                                        }
+                                    }
+
                                     Typecho_Cookie::set('__typecho_config', base64_encode(serialize(array_merge(array(
                                         'prefix'    =>  _r('dbPrefix'),
                                         'userName'  =>  _r('userName'),
diff --git a/var/Typecho/Date.php b/var/Typecho/Date.php
index ed27541d..cbc42c66 100644
--- a/var/Typecho/Date.php
+++ b/var/Typecho/Date.php
@@ -127,6 +127,6 @@ class Typecho_Date
      */
     public static function time()
     {
-        return self::$serverTimeStamp ? self::$serverTimeStamp : (self::$serverTimeStamp = time() - idate('Z'));
+        return self::$serverTimeStamp ? self::$serverTimeStamp : (self::$serverTimeStamp = time());
     }
 }
diff --git a/var/Typecho/Db/Adapter/Mysqli.php b/var/Typecho/Db/Adapter/Mysqli.php
index edf99660..5a40bec4 100644
--- a/var/Typecho/Db/Adapter/Mysqli.php
+++ b/var/Typecho/Db/Adapter/Mysqli.php
@@ -31,7 +31,7 @@ class Typecho_Db_Adapter_Mysqli implements Typecho_Db_Adapter
      */
     public static function isAvailable()
     {
-        return extension_loaded('mysqli');
+        return class_exists('MySQLi');
     }
 
     /**
diff --git a/var/Typecho/Db/Adapter/Pdo.php b/var/Typecho/Db/Adapter/Pdo.php
index 1c1de13c..d1cd9375 100644
--- a/var/Typecho/Db/Adapter/Pdo.php
+++ b/var/Typecho/Db/Adapter/Pdo.php
@@ -39,7 +39,7 @@ abstract class Typecho_Db_Adapter_Pdo implements Typecho_Db_Adapter
      */
     public static function isAvailable()
     {
-        return extension_loaded('pdo');
+        return class_exists('PDO');
     }
 
     /**