I recently installed El Capitan 10.11.4. It has downloaded and installed as an upgrade from 10.8.5. and when I tried to shut down or restart my machine froze on the desktop screen with Finder invisible. I've been reading on the apple support communities that this is a common problem and it seems to be twofold: 1. USB ports stop working 2. Machines don't power down/up normally. People have been told at the apple genius bar to back up their data, do a complete wipe/clean install and manually re-install programs one by one. Less than ideal. I have noticed that a this happens a lot to people that are running audio programs on their systems and some people have been able to solve the problem by removing .kext and/or preferences files from Avid and Native Instruments, which seem to be in conflict with El Capitan. I do run a lot of audio programs myself so I might have to do a lot of rummaging in /Library/// territory before I find the culprit. I did a clone of my boot drive before I installed El Capitan, so I just reverted back to that clone (10.8.5, which is rock solid) Anyone here have a similar problem and found a solution to this?