Comment 2 for bug 532183

I have exactly the same problem. I activated auto-login with GDM and first time I'm prompted for a password, I type it in the dialog box, press Enter and the session is closing and I'm at GDM login. If I validate my password clicking on the "Validate" button, all is fine and the session is not closed.

I'm also using nvidia proprietary driver under up-to-date Lucid Lynx.

They seems to be the same bugs as :

https://bugs.edge.launchpad.net/ubuntu/+source/xorg-server/+bug/530781
https://bugs.edge.launchpad.net/ubuntu/+source/xorg/+bug/532047