I installed the latest drivers for my Fireface Uc, with the latest firmware.
After running Ableton live, And other applications like Adobe lightroom,Google chrome and Itunes on the background, I had a crash :

There are a digital sound and after a total silence. I have tried to restart the fireface, but after a few seconds the same thing.
I think it is a problem between the soundcard and USB ports..

My setup : Fireface Uc, Macbook late 2009, 10.8
Driver: 1.75, firmware: 115.

Thank you for the help ( and sorry for my bad english )