Hezul

I decided to do a little test. I installed Line 6 Monkey 1.68 on my MacBook Pro which has Pro Tools 10.3.9 installed without any AVID drivers. Monkey wouldn't launch on that Machine either.

Well, Pro Tools runs very, very poorly on Yosemite. 10.10 threw CPU spikes all the time, but now with 10.10.1 things are a tad more stable. I've had a lot of problems with Digi 002 and Yosemite, and I think that it's the drivers that are causing the problems. I don't think that it'd be strange if Avid's drivers turn out to be the root of the Monkey problem. If they stop some of Native Instruments programs from launching, why wouldn't they do the same to other similar products?

Thank you for the info. I have Pro Tools 10 and 11 and Sibelius 7 and 7.5 installed on an iMac. Maybe we're getting somewhere here.

I think the Line 6 Monkey launch problem might have something to do with Avid's drivers. It seems to be a known issue that any Avid driver under Yosemite stops Native Instruments controller dependent programs (e.g. Guitar Rig) from launching. I've got the 003-Family Driver installed, and neither Guitar Rig or Line 6 Monkey are launching on my computer. Could someone who's having the Monkey launch problem let us know if he or she has Avid drivers installed on his or her system?

I'm having the some problems as everybody else in this thread. I managed to update the driver, but I can't get Line 6 Monkey 1.68 to launch with or without the hardware connected. I uninstalled Monkey following the instructions you posted. I'm using POD x3 Pro and an iMac (mid 2011). I also have a Digidesign Digi002 hooked to my machine, and my X3 Pro is hooked to the Digi002 via S/PDIF. The Digi002 is having similar issues too.