Recently I've updated to WP 3.4 using the qTranslate.php provided in the trunk (trac.wordpress.org) 8 days ago.
After having done this update WP-Admin doesn't redirect properly anymore. That means as soon as you confirm an action such as saving an article, updating interal WP options, logging in or logging out WP-Admin returns with a blank page only and not with the page that is usually expected to appear.
I've deactivated all plug-ins to find out what's going on an I can reproduce the above behaviour as soon as qTranslate gets activated again.
Please fix that error. I've even donated since to me qTranslate is the best multi-lingual plug-in for WP.