Cannot restart Mac, Finder issues in El Capitan I've been having some issues with an iMac running El Capitan. The issue seems to be Finder. I tried leaving it to shut down by itself overnight to no avail. 

On occasion I get this message: The screenshot below is Dutch but says something along the lines of: 


  Your Mac was not shut down because Finder could not be stopped. Please quit ?Finder to continue. 




Things I've tried


I've tried shutting it down with a hard reset (power button and a shutdown command from terminal) and restarting. 
I've tried disk repair in recovery mode, 
I've tried resetting NVRAM.
I've tried shutting down Finder with the usual suspects: Force Quit, killall Finder. 


This last one does something, but definitely not what I expect:  

 

It looks like Finder has quit, it's no longer in the list activity monitor. Relaunching it with terminal command open . in the user home folder gives the error: 


  LSOpenURLsWithRole() failed with error -600...


Don't know how to fix it anymore. Any advice?
My issue turned out to be in an outdated Wacom driver. After removing it, Mac worked fine. I guess formatting would have sorted it out too.