There's an incompatibility between the NEC chip found in some Firewire cards and the motu firewire line of interface.

If the firewire installer warns you that you're running a Firewire card with the NEC chip, you should replace said card with a card that uses the TI (Texas Instruments) or Lucent chip. Keyspan, Sonnet and ADS are a few of the many brands using the TI or Lucent firewire chips.

Please check with the manufacturer of the firewire card before purchasing it to ensure it has the TI or Lucent chip.