I can confirm this. It happens with either gdm or kdm, but only on a KDE session. I'm running Ubuntu Edgy with the latest updates as of a few hours ago.
-- kdm blocks in xdmcp without disk activity https://launchpad.net/bugs/51337 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs