Can not startup X window after some services are stopped.

Issue

• Can not startup X window after some services are stopped with the following error in var/log/messages.

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init: prefdm main process (1869) terminated with status 1
init: prefdm main process ended, respawning
…
（same error has happened repeatly）
…
init: prefdm main process (2030) terminated with status 1
init: prefdm respawning too fast, stopped
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