再起動したら X の起動に失敗している……
Xorg.0.log を見るとデバイスが見当たらない?

[ 39.614] (EE) No devices detected.
[ 39.614] (EE)
Fatal server error:
[ 39.614] (EE) no screens found(EE)
[ 39.614] (EE)
Please consult the The X.Org Foundation support
         at http://wiki.x.org
for help.
[ 39.614] (EE) Please also check the log file at "/var/log/Xorg.0.log" for additional information.
[ 39.614] (EE)
[ 39.665] (EE) Server terminated with error (1). Closing log file.