I have recently downloaded and updated to the latest version of Capture One. Every time I try and open Capture One, the program 'locks up' and eventually force quits. I have tried to delete all Phase One files in the preferences folder along with all contents in the User/ Library / Application Support / Phase One / Chroma Calibrations. I have deleted Capture One from my Applications folder and tried to reinstall it again. None of those options worked eventually.
There are some conflicts and crashes due to the software "You Control Desktop" from the website http://www.yousoftware.com with additional programs called "You control fonts" and "You control Tunes". Once these programs are disabled, Capture One Software should work fine.
Please try to disable the programs mentioned above in your system, reinstall Capture One, and relaunch it. That way, it should work properly.