sometimes my F15 doesn't boot

[Eric Doutreleau]

Hi

i m using F15 with the latest updates

and from times to times my machine doesn't boot.
it seems to hang just before starting X

Fortunately i can ssh to it and i see the following thing

systemctl list-units | grep dead
getty(a)tty2.service        loaded inactive   dead      start Getty on tty2
getty(a)tty3.service        loaded inactive   dead      start Getty on tty3
getty(a)tty4.service        loaded inactive   dead      start Getty on tty4
getty(a)tty5.service        loaded inactive   dead      start Getty on tty5
getty(a)tty6.service        loaded inactive   dead      start Getty on tty6
plymouth...t-wait.service loaded inactive   dead      start Wait for 
Plymouth Boot Screen to Quit
prefdm.service            loaded inactive   dead      start Display Manager
getty.target              loaded inactive   dead      start Login Prompts

How can i debug this problem?


-- 
Eric Doutreleau