I have posted about same problem 2 weeks or so ago
"N6 and Artist Control"viewtopic.php?f=194&t=57152
What I did get from Steinberg Support is:
Currently the issue appears to turn out as a system specific problem.
Most of the crashes related to EuCon are caused by calls to the Apple AppKit and / or WebKit (also in this case).
So, to bring probably some intermediate relief in this case, here is a list of things to check / do:
-- Make sure no web-based applications are running when using Nuendo
-- Possibly disable toolbars from the browser(s)
-- Perform Repair Disk Permissions
-- Un-install and re-install the EuCon adapter
The behaviour has been further improved in the latest Cubase Update 7.5.20 .
However Nuendo users will have to wait some more...
in the meanwhile, it is worth a double-check.
The "things to check" didn't help in my case. Perhaps we have to wait for 7.5.