..So I tried the steps detailed here and now my GUI is gone....
Ah, the advice you found dated Thu Feb 01, 2007 2:10 am was valid for his (4.0.1 or maybe 5.1.x ?) Knoppix before Debian 'Etch' was formally released as Debian 'stable', thus rendering obsolete many of the URL definitions in the Knoppix /etc/apt/sources.list file .
Your easiest way to restore your system from whatever is its present condition might be to re-install, although you might be able to rescue it from a console, updating your /etc/apt/sources.list as described in the forums e.g.
http://www.knoppix.net/forum/viewtopic.php?t=27800 Posted: Mon Aug 13, 2007 8:30 am
and so on.

This thread
http://www.knoppix.net/forum/viewtop...759&highlight=
discusses some aspects of media management and hal, dbus which may help your original problem.

But really, for a much easier life, have you tried installing 'proper' Debian ? Please see
http://www.knoppix.net/wiki/HD_Insta...g_not_to_do_it