Interesting… I’ve never had this issue in Fedora KDE, which I run on my PC, but exactly the same thing happens on my wife’s PC and the HTPC which both run Xubuntu. Tried setting screen saver, power save options and eventually even uninstalling the screensaver completely. At least in my case it’s caused by Xorg DPMS if I remember correctly. Fixed it a while ago but then it came back on one of the computers at some point. Check out wiki.archlinux.org/…/Display_Power_Management_Sig… if it could be the same for you.