Bug#384353: kdm locks keyboard, keeping user from typing username/password
i'm not sure it's caused by kdm. Have you updated recently your system ?
strangely you've got on your system:
ii libx11-6 6.9.0.dfsg.1-6 li
ii libxau6 1:1.0.0-3
ii libxdmcp6 1:1.0.0-4
ii libxtst6 1:1.0.1-5
ii xbase-clients 1:7.1.ds-2
have you seen the thread on debian-devel about:
Incorrect version of xserver-xorg in unstable
xorg has been uploaded in unstable instead experimental by mistake.
Maybe you are affected by this mistake.