Firewire disconnect issues

Twice I have had my mixer shut down during a show because the computer has disconnected the firewire interface. Once because the computer went to sleep and the other when the cable was accidentally knocked loose.

I can reproduce the behavior by pulling the firewire cable out of the PC with the mixer and about 75% of the time it will fail. At best, the board will pop like it was just turned on.

I have reset the firmware a couple of times.

Is this expected behavior? Does this behave the same way with a MAC?

I'm using the Win7 with the StarTech EC1394A2 Expresscard (VIA chipset).

Thanks.

-Bruce