I'm running Xubuntu 18.04 on an HP Pavilion laptop. When I turn on the laptop, I can login and everything is fine. However, when I close the laptop lid and open it again, I can login but after that I have a black screen from which the laptop won't wake up.
To fix this I set the laptop to lock the screen but not suspend when the lid is closed. However, this work-around reveals unintended side-effects when I turn on syndaemon through the Setting Manager. Now whenever I open the laptop lid, the touchpad can't move the cursor.
I'm hoping someone might have a solution to the black screen problem that doesn't cause syndaemon to mess up. I've also tried to replace the gtk greeter with the webkit one, but the webkit greeter crashes when I login for the first time after installing it and then exhibits the same faulty behavior as the gtk greeter when I subsequently open the lid.