I have not tried these installs so I am just making some general assumptions.

If your monitor is not properly identified and configured, then Knoppix can overscan it causing it to go blank just as it would if you deliberately overscanned it in Windows. You can test this a couple ways. Press ctl-alt-(keypad+) or Press ctl-alt-(keypad-) to step through several scan modes. You may see the monitor come back to life. If this is the case, use the "knoppix xvrefresh=60" boot option to force knoppix to run your monitor at 60hz or the "knoppix screen=800x600" to force knoppix to run at the resolution you specify.

Alternatively, you can verify that the machine is still alive by checking one of your virtual terminals. Press ctl-alt-F2. You should see "root@tty2[/]#" If this is the case, it confirms the same problem already discussed in the last paragraph.

I hope this is helpful.