Been using logic for years - including last 3 years with a Mackie Control Universal Controller, linked to an RME Fireface 800 audio / midi interface. I've never had a single problem with the MCU. Since moving to OSX Lion / Logic 9.1.5 I have a constant problem with the master fader on the MCU jumping to 0 ( and the same on screen ). There are temporary work around such as delete the fader .cs file, or remove the controller from Logic / Preferences / Controllers etc. and re-scanning it but these are all just work-arounds. The two things that get said to this question are generally a) do you have any automation - answer ( no ) not on the master fader and I have reproduced this problem with a blank empty project - just by pressing play. b) do you lots of midi events going on - answer sometimes yes, sometimes no but it makes no difference. c) are your midi cables ok - answer ( it works with my old mac ). I have two youtube clips ( poor quality picture and terrible sound ) but it's an example at least of what's happening. You need to watch the entire clip to get the full picture. Any help so very much appreciated - please be nice to me I'm having a really bad day..... http://www.youtube.com/watch?v=2xzdFaQc8k8 http://www.youtube.com/watch?v=bPJ1QLqJFB8 Apple have logged this as a potential bug. They have one or two other similar cases but it's not definite. I'd prefer it if it was something I'm doing. Thanks Martin.