Recent Upgrade Broke Xscreensaver (solved)
I had made some changes to /etc/apt/preferences and did an:
# aptitude full-upgrade
A bunch of packages were upgraded to unstable, and the end result was that something in the upgrade made xscreensaver scream and die.
I'd get the error message telling me that the xscreensaver daemon wasn't running (even though I have it in my KDE Autostart directory) and would I like to run it, I say "yes" and then I'd get the error message telling me something to the effect that "xscreensaver daemon did not start up properly" and that I should check my $PATH.
Thus, xscreensaver wasn't working. But KDE's less-than-perfect screensaver did work. But since kscreensaver is not xscreensaver, it is, therefore, inferior, and not worth using....
I looked through the appropriate log in /var/log/ and noted that xscreensaver wasn't upgraded. Hence, the problem was not with xscreensaver but with something else that was no longer playing nice with xscreensaver. I noted that some xserver-xorg-* packages had been upgraded, and I guessed that the problem was in this particular set of upgrades.
My xorg.conf file had not been changed since July, so the problem wasn't in there. I didn't have any permission-related problems with respect to executing xscreensaver. I exhausted every possible configuration-related problem that I could think of. So, the problem had to be package-upgrade-related.
I took the lazy way out and downgraded both of the xserver-xorg-* packages that were upgraded to unstable back to testing. And the problem was corrected.
I'm not sure what the problem was, and I had not collected enough relevant information to write up a bug report on the problem.