<html> <head> <meta http-equiv="content-type" content="text/html; charset=utf-8"> </head> <body bgcolor="#FFFFFF" text="#000000"> lightdm + lightdm-gtk-greeter It is OK if I start computer normally. But when I locked screen with 'dm-tool lock',and light the screen again.My screen just flashes. I can see the login panel moves very fast from right to left on my screen. I can input my passwd, and login my system, but the screen just blacked after I succfully logined in. I had to use 'xrandr --output eDP1 --off && xrandr --output --auto' to light my screen again. here is an image when the screen flashes: <img alt="" src="cid:part1.06010301.03040802@gmail.com" height="960" width="1280"> </body> </html>