[G4] FW problem

[Roxylee]

Hello, smart people. I'm having major FW issues and wonder if anyone  
in here has encountered the same problems, and if so, what they did to  
fix it. My computer is a Quicksilver 2002, pumped up RAM, running  
under Leopard. Less than a year ago I bough a FW audio interface  
(Saffire) and after 10 months, it started shutting down the computer  
before it could fully boot up. After trying a few times, it was fried  
altogether and the built in FW port seems to be fried, too- at least  
it's not working.. I bought another card and the company sent me a  
replacement unit. That interface also fried  but the new card still  
worked when the iSight cam was plugged in. The company sent me  
*another* unit, and after using it for 3 weeks, it, too, fried. Now  
neither FW card works, or maybe the iSight is fried? When I plug it  
in, the green light goes on and it makes a sound like it's on, then  
after a few seconds, the light goes back off. All FW ports on my  
machine are not working. When I went to Network prefs, it says: PCI  
Firewire slot 2 not connected, and Built in Firewire inactive.

I unplugged everything but the usb keyboard and mouse, unplugged  
everything, waited 10 minutes, and rebooted. Same status.

All software and drivers are up to date, and the units are definitely  
fried- the first one was sent to a repair place and they said it would  
cost more to fix it than to replace it. The FW ports on the back of  
the last one had a definite ozone smell. The units. according to the  
phone tech, are hot plug-able, although I hadn't touched the plugs on  
the last one, just left them plugged in whenever the computer was on.  
I was only using the unit for an XLR condenser mic and headphones. I  
tried it with a new cable, too.

They are replacing the unit again, but I'm afraid to plug it in once I  
buy yet another card. I don't want to replace the whole logic board if  
it's not necessary. Does anyone know what could be causing this and  
what I can do to fix it?  Everything else seems to be working. Disk  
Utility isn't reporting any problem, and I don't have another utility  
to check it. I'd appreciate any help, in simple non-tech talk.:-)

Thanks,

Roxy