my knoppix was working well, I installed vnc4server, it also worked well. Today I started the machine and to my surprise I cannot enter runlevel 5, it gets stuck. For some time tries, i.e. goes blackscreen, and then back to console with message:

# The graphical subsystem could not be startet
or terminated unexpectedly.
Maybe your graphics adapter or monitor are not auto-configurable.

Please try to reboot and give some of the Knoppix-Cheatcodes
at the initial boot:-prompt, which match your graphics adapter.
knoppix xmodule=radeon (or ati, nv, cirrus, ...)
knoppix xmodule=fbdev
knoppix xmodule=vesa
knoppix hsync=90 vsync=75

I don't remember doing much more that installing vnc...

I've looked around the network and didn't found any useful hints. Any ideas what my go wrong? Where to start checking?