我刚刚安装了Ubuntu GNOME 14.04 LTS，一切正常。
但突然它冻结了，然后变成黑屏，并显示以下内容：
* Stopping System V runlevel compatibility
* Stopping save kernel messages
* Starting crash report submission daemon
[ 797.944847] nouveau E[Xorg[1052]] failed to idle channel 0xcccc0000 [Xorg[1052]]
[ 812.930255] nouveau E[Xorg[1052]] failed to idle channel 0xcccc0000 [Xorg[1052]]
[ 827.971609] nouveau E[gnome-shell[1911]] failed to idle channel 0xcccc0000 E[gnome-shell[1911]]
[ 842.957016] nouveau E[gnome-shell[1911]] failed to idle channel 0xcccc0000 E[gnome-shell[1911]]
[ 1304.084012] nouveau E[Xorg[3342]] failed to idle channel 0xcccc0000 [Xorg[3342]]
[ 1319.069420] nouveau E[Xorg[3342]] failed to …