We have confirmed that when using an SL 4 or Rane Sixty-Eight on Mac OS X 10.7.3 and above it is possible you may get a Kernel Panic when connecting your unit while Scratch Live is open. This does not affect any other Rane hardware.
1) Connect your SL 4 before opening Scratch Live, and disconnect the SL 4before closing Scratch Live.
2) Note: Workaround (2) will render using your Rane SL4 unusable as a ASIO soundcard while the .Kext is removed from your 'extensions' folder.
Close all programs.
Go to location - Macintosh HD > System > Library > Extensions > Remove to desktop files : 'Sixty-Eight.10.6.Kext' & 'SL4.10.6.Kext'. This should allow you to hot plug your Rane hardware device without Kernel Panics.
To use again replace your .Kext related hardware file back into the extensions folder.
These workarounds only work for OSX Lion users, not Mountain Lion OSX users.
This is an issue which we hope to fix in a forthcoming release of Serato Scratch Live.