[G4] QS powers down

[Roxylee]

Hi, can anyone shed some light on why this is happening? My G4 QS  
2002, running Tiger, has been intermittently shutting down right  
after the desktop loads, but only when my audio interface (Saffire LE) 
is plugged in. This is something that has been happening  
intermittently for a few weeks. Yesterday I was able to start it up  
and record; today it shut off again. I can't afford to start  
replacing parts as trial and error. I hope the motherboard isn't  
being fried every time I start up the G4. Has anyone ever encountered  
such a problem? Any advice would be greatly appreciated. Thank you. :-)