I use qTranslate to multilingualize my posts.
Saidly installing it overwrote some translations that have been working before. For example, “Hinterlasse eine Antwort” (german) should be shown instead of “leave a reply”, which isn’t.
The solution: (Re-)Install the latest translation files:
Download them from:
http://svn.automattic.com/wordpress-i18n/de_DE/trunk/messages/twentyeleven/
Files: *.po and *.mo, copy them to:
[WordpressInstallation]/wp-content/themes/twentyeleven/languages