why does xscreensaver fail so often?
 

I love xscreensaver, but I find that too often (say 20% of the times) it fails to start a screensaver.

Normally the message is something like:
xscreensaver: unrecognized visual "any"
xscreensaver: blah blah process ID (process name) exited abnormally (code 1).
on a black screen.

Is it that I made a mistake configuring it?

It's a kubuntu breezy box.

in your xscreensaver configuration tool, go to settings, then to advanced... there you will see an option called visual... yours is set to "any", so try changing it to something else, like "GL" or something...