1. Check if you have both light-locker and xfce4-screensaver installed. If you do, you should be able to safely uninstall light-locker.
2. It could be related to graphics. Please run `inxi -G` and provide the output so we can identify your graphics card and driver.
There's a few possibilities:
1. Check if you have both light-locker and xfce4-screensaver installed. If you do, you should be able to safely uninstall light-locker.
2. It could be related to graphics. Please run `inxi -G` and provide the output so we can identify your graphics card and driver.