I have the same problem in a clean installation of Kubuntu Edgy (although my home directory already had stuff in it). In particular, I can also get around the problem by restarting the X server using Ctrl-Alt-Backspace.
My graphics card claims to be a 01:00.0 VGA compatible controller: nVidia Corporation NV18 [GeForce4 MX 4000 AGP 8x] (rev a4). (FWIW, montior is an iiyama ProLite 435S). -- Colour depth problem on one display following upgrade to edgy https://launchpad.net/bugs/71094 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
