I'm seeing an occasional random squeal for a second or so through the Fireface UC on OSX (2010 i7 Macbook Pro).  Latest 1.48 drivers and UC firmware.
I've tried everything to make it go away, but it's killing our live performances.  Sometimes it's good for an hour next time we get one 20 minutes later.
It happens in iTunes in between sets and it happens in Studio One as we are performing.
I've never had the problem on my i7 desktop running Windows 7.  So I'm thinking of bootcamping the mac and see if Windows 7 performs any better on it.

Thoughts?