Can't customise screensaver in KDE?

When I select Media or Slide Show for screensaver, after browsing to the
directory I want to use and selecting it, all I get is is an ugly grey
screen. I’ve checked the help, but couldn’t find anything about this. Is
this a KDE4 bug, or an RC1 bug?

Has no one else experienced this, or have any suggestions on how to fix it?

Sorry for bringing this up again, but the problem persists in RC2, and was wondering if anybody had any ideas at all before I upgrade to Gold?