kubuntu amd64 - Failure on logout

[Tim Johnson]

Using ver 7.04 - the recently much dicussed amd64.
I ran updates on July 21.
I am now booting with the newly installed kernel:
## from /boot/grub/menu.lst
title       Ubuntu, kernel 2.6.20-16-generic
initrd      /boot/initrd.img-2.6.20-16-generic

When I choose Logout->Logout, instead of seeing KDM,
All I have is a black screen, and is unresponsive, have to do a had
reboot to restart.

I'd appreciate any and all help on this. I've recently migrated from
Slack 10.0 - as for diagnostics, etc, I'm not a system guru, but am
a programmer and familiar with the command line, vim, mc - etc.

thanks
Tim