I am stopped cold and unable to continue a recording session, since upgrading to Yosemite. Upon playback, I get a "disk too slow and system overload" error that stops the playback. computer: Mac Pro early 2008 w/2 2.8 Quad Core Processors running 10.10 Yosemite, 14 GB RAM ,Nvidia Ge Force GT 120 graphics card. There are only (2) tracks with anything going on on this new project . The session is playing a MIDI instance of Addictive Drums on one track, and I am accompanying it on another track live with a Logic Steinway piano being played on a Korg keyboard connected with a MOTU Fastlane USB. I had no issues whatsoever with this same project/configuration with the previous OS (Mavericks). Completely shut down and frustrated.