I used a dual boot loader (booting).
I've reinstalled knoppix all over and used GRUB.
Now it boots ok but the image is unstable, comes and goes avery like 2 seconds.
I get the debian login screen and KDE desktop, everything seems to be working except for this problem with the screen going black.
I guess the video card is not properly configurated, and I like to know how can I fix it.