I can also confirm this on Debian Squeeze, from various users with different hardware, with different Window Managers.
Pressing the Enter key about 5-10 minutes after logging in via Gdm causes an automatic logout to Gdm.
It has happened in the terminal, on Iceweasel, Firefox, Arora.
Points to a broken xorg update as it didn't happen before the update.
I can also confirm this on Debian Squeeze, from various users with different hardware, with different Window Managers.
Pressing the Enter key about 5-10 minutes after logging in via Gdm causes an automatic logout to Gdm.
It has happened in the terminal, on Iceweasel, Firefox, Arora.
Points to a broken xorg update as it didn't happen before the update.