I had this happen on my [iMac 27"5k 3TB fusion model] whenever I tried to open one of my files with a massive amount of video files where the settings were set to "Quicklook" ... pretty much froze the whole computer although I could move from app to app and move the mouse... it was the Finder that had the spinning beachball. I found if I changed to "List view" it kinda fixed it but I really need Quicklook in this folder.
Also, I find that if I use the zoom mode with the control key and mouse that it will eventually freeze the mac with the exact same " I could move from app to app and move the mouse" but that was all... needed a forced restart again.
I've never had a mac OS update that needed as many forced restarts as this one... that and the fact they haven't even added the new way to read massive image files for the fusion drive yet... sloppy IMO. I doubt Steve would have allowed this to hit the app store without that major aspect missing [outside of beta].
Also, Safari is buggy... not so much in the way it works but in the way it looks with items in the toolbar becoming blank [i.e. the icon inside disappears after a couple of hours]... again pretty sloppy.
Another thing is that Quicklook occasionally misses item pictures [see attached image] in the window but it is actually there if you hit the spacebar. I've even had it shimmer bright red in the background.
There are loads of other little niggles that make me conclude that this is the buggiest update I have ever experienced - and that's going back to OS 6, old school!
when I said it shimmered red I meant that all the background grey here would occasionally turn red and shimmer if I used the arrow keys on the keyboard.
Network Diagnostics have also disappeared from System preferences... really?
Not impressed Apple, not impressed at all.
