Confirmed, same problem, compiz workaround fixed it.
Ubuntu 9.04 (Gnome), Compiz 1:0.8.2-0ubuntu8, Yakuake 2.9.4-0ubuntu1, KDE 4:4.2.2-0ubuntu1, QT 4.5.0-0ubuntu4.1, Nvidia 180.44
Confirmed, same problem, compiz workaround fixed it.
Ubuntu 9.04 (Gnome), Compiz 1:0.8.2-0ubuntu8, Yakuake 2.9.4-0ubuntu1, KDE 4:4.2.2-0ubuntu1, QT 4.5.0-0ubuntu4.1, Nvidia 180.44