[bob2014]

Consistent: Pro Tools QuickTime Server (Not Responding)
As I boot Pro Tools, that shows up in Activity Monitor even before I open or create a session, and remains that way until I quit Pro Tools.

Pro Tools 2018.1.0
macOS 10.12.6
MacBook Pro 13" 2016, Intel Iris Graphics
MBox Pro 3rd gen, as well as Scarlett 2i4

I'm not doing any video playback currently.

Regarding: "... launch QuickTime Player 7 and go into Preferences, deselect the "Show Content Guide automatically" and then quit QT7. Launch your ProTools/Media Composer and the problem should be gone.", I've had "Show Content Guide automatically" deselected for years now. (For good measure, I just toggled that back on, launched Pro Tools, quit PT, deselected that option and quit QT Player 7, then launched Pro Tools, but the problem remains.)

I have sampled the not responding process and would be glad to send to Avid engineers (it is quite large for me to post here).