When I boot up kubuntu I'm greeted with a nice login screen that has an option 'button' located near the bottom of the screen. I can login with no problems but when I log out the login screen appears to be resized and the session options button is no longer visible.

I can still login without a problem but if I want to use a different session I have to ctl-alt-bksp and restart X. Restarting X doesn't always fix the login screen and I have to restart the system.

I've never seen X behave this way before and have no idea what's going on, much less how to fix it. Any suggestions would be welcome.

Using nvidia 6200, dual monitor setup, kde4.1.

I turned off "use theme login" in the login manager and that fixed the buttons disappearing act. The login screen is now ugly by comparison but oh well, it works.