I think it's the orangemicro piece of **...errrrr Firewire Card. I remember someone else posting a similar problem here a while ago.
FWIW, I run my EzQuest Boa 8/4/32 without changing my loaded extension set, without rebooting, after force quitting other stuff
and I've yet to make a Coaster (well, none that were not MY fault
The drive is very good, except for the audio "blip", but Ezquest Tech support says they're working on it. (rather, they say adaptec is working on it, but you get the idea)
-sean