1) I upgraded my gaming computer from Windows 7 Pro to Win10 Pro a few weeks ago. I went to do a basic copy to external storage of a large group of files for cold storage (roughly 500GB). I do this every few months but last night, it gave me out of memory error (RAM) during the copy. I've never had a that kind of error under any previous version of Windows.
2) Previously I was running a mix environment of Mac OS X, Windows 7 Pro, and Windows 10. When I share a folder on Windows 7, the Mac OS X picks up the subfolders correctly. But Windows 10 machines will decide to show only half or sometimes only one of the subfolders. After upgrading all my windows machine to Win10, the problem went away. Can't help but think MSFT is sabotaging Windows 7.
3) Sometimes on Windows 10 machines, I can't right click on the File Explorer icon to open another instance of File Explorer.
4) After each patch Tuesday, several of my machines will decide to go to 640 x 480 when they boot up the next morning. Not a huge deal, but gets annoying to redo the resolution every Wednesday. No driver issues or anything, the machines just feel like booting Windows 10 at 640 x 480.