I installed Atmel Studio 7.0.1006 on a clean Windows 10 installation.
Whenever I attempt to close AS7, the dialog shown below is displayed:
The only way I'm able to close AS7 is to kill the task in taskmanager.
Windows File Explorer finds CefSharp.Core.dll here:
The only 'odd' thing about my installation is that AS7 is installed on "K:" drive rather than the default "C:" drive.