Failsafe does almost no hardware detection. Since you can boot with failsafe it is only a matter of discovering which device or feature Knoppix does not like. You will need to implement one or more of these cheat codes:
http://www.knoppix.net/docs/index.php/CheatCodes

I would start with this: (only type what is in bold)

boot:knoppix noapic noapm nopcmcia nousb

If it boots then you know that one of these four things is causing Knoppix not to boot.

apic - advanced programmable interrupt control
apm - advanced power management
pcmcia - your modem or network card
usb - self explainatory

Assuming it boots with these cheat codes, the next step would be to eliminate each of these as a possibility like so:

boot:knoppix noapic-if that doesn't work then:
boot:knoppix noapm...and so on...
boot:knoppix nopcmcia
boot:knoppix nousb

If you need assistance with the other cheat codes (language, wheelmouse, screen resolution etc. just post back.