If you set a default user in kcontrol, KDM doesn't show it but it shows the last user that logged out (found on kde 3.3.4) Reproducible: Always Steps to Reproduce: 1. Set a default user for the login window in kcontrol 2. Log off (or open another kdm session) Actual Results: The user written in the username box is not the default one, but the last user who logged off. I've found a simple solution for this problem. Find this line: PreselectUser=Previous and change it into: PreselectUser=Default Then restart kdm and it should work.
This is discussed here for kde 3.3.x: http://bugs.kde.org/show_bug.cgi?id=88339 It seems kde 3.4 doesn't have this problem.