I'm one of the core-developers of Manjaro Linux, an archbased distro. We are using kalu as our update-notifier. First, great work mate.
Carl Duff our document-manager just wanted to create a nice tutorial how to use kalu using Virtualbox. As soon as he tries to start the GTK gui VirtualBox freezes showing gksu dialog. You're forced to kill Virtualbox.
This happens every time. I tested it myself on Manjaro 0.8.2rc2 image. To quick-fix this issue I might uninstall kalu from my install-media when Virtualbox gets detected.
Maybe you find some time to try it out yourself using Archlinux or if you want any Manjaro Linux install media.