On a system running the K Display Manager, when is the /etc/kde4/kdm/Xreset script automatically executed?

The `Xsetup` script is typically executed when the KDM starts an X server, not the `Xreset` script.

The `Xreset` script in KDM (or other display managers) is designed to run after a user logs out and their X session ends. Its purpose is to perform any necessary cleanup, reset permissions, or restore system states before the next session starts.

KDM crashing is an unexpected failure, and the `Xreset` script is for planned session termination, not for error handling.

`Xreset` runs after a user's session ends, not specifically when the underlying X server is restarted, although restarting X might implicitly end sessions.

An X crash is an unplanned event, and `Xreset` is part of the normal session termination process, not an emergency handler.