I/O errors usually (not always) indicate that the CDR is either bad or burned too fast (4x or 8x recommended). OR I/O errors can also be caused by ACPI and APIC conflicts.

Knoppix boots with a splash screen. At that splash screen you can enter codes which will force Knoppix to do certain things. Theses codes are known as Cheat Codes.
To test the CDR, use:
knoppix testcd

To disable APCI & APIC:
knoppix acpi=off noapic