Sometimes the Apple CoreAudio driver has difficulty connecting to the Saffire PRO 26 i/o. If this happens, it may cause the Mac to crash when re-setting the unit.
If you find that your Mac is crashing when you connect the Saffire PRO 26 i/o, then you will need to have the Saffire PRO 26 i/o attached to your Mac and turned on before powering up your Mac.
Alternatively you can put your mac to sleep when attaching the Saffire pro 26IO then wake it up.
This issue will be fixed in a future release of OSX (post 10.4.8).