I cannot install Joomla (on Ubuntu 12.04, Apache, MySQL). All required prerequisites seem to be met, but after hitting the final install button, a popup appears (see attached image), but nothing happens. Also, a check on the server seems to indicate that no files or mysql activity takes place.
I retried with several different versions of Joomla, without success.
What can this be, or where can I look more closely what is supposed to happen at this very stuck moment?