Or you can do what I do...
Change your settings to take you into a terminal instead of a graphical login manager... then create/edit ~/.xinitrc to read something like this:
Thats what I use... or 'startkde' for KDE 3.2 Just have to find out what the command is. Im not sure what it is for Blackbox.
I dont know if Debian is that much different, but just though I would throw my two cents in
