When I run Knoppix on this Hewlett Packard machine, I get a typical boot up until I run X at which point I get a black screen. I have tried the following suggestions found on this forum.

failsafe
expert (looks like from the expert output nv is detected anyway)
knoppix xmodule=nv
knoppix xserver=XF86_SVGA
knoppix xserver=XF86_SVGA xmodule=nv
knoppix 2 (this works fine but I get no X. When I run startx I get the same black screen)

This video card is an NVIDA riva TNT2 model 64 (HP) and it is not an onboard video card.