I think this is an old bug but I didn't find anything useful with google.
So my problem is that the screensavers sometimes don't start automatically after the desired idle timeout. As I observed it doesn't depend on the type of the actual screensaver (GL or not). Once KDE gets into a state where one screensaver failed to start, no other won't work, regardless of what I select in the "Configure Desktop / Screen Saver" menu. Only a KDE (or X) reboot will help. Of course all the screensavers work just fine if I test them, but they won't start automatically. My settings usually are: start automatically; aware of power management; require password.
Thanks for any help,