Index: includes/language.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/language.inc,v
retrieving revision 1.14.2.1
diff -u -p -r1.14.2.1 language.inc
--- includes/language.inc	2 Jan 2009 23:37:48 -0000	1.14.2.1
+++ includes/language.inc	27 Mar 2009 12:10:45 -0000
@@ -59,6 +59,11 @@ function language_initialize() {
 
   // Browser accept-language parsing.
   if ($language = language_from_browser()) {
+    // If the language is set from  browser preferences, set CACHE_DISABLED
+    // to avoid caching the page in this language for subsequent requests.
+    if ($language != language_default()) {
+      $GLOBALS['conf']['cache'] = CACHE_DISABLED;
+    }
     return $language;
   }