Have you suddenly discovered your Mac reading everything out loud on the screen, and then navigating with a thick black box ...

This is usually the same issue as above: locked files, folders, or permissions errors on those items in the filesystem. To fix both of the above errors, you'll need to change the permissions in ...

In a pinch, lift the Mac mini off of a metal enclosure with a single plate to get some distance between the metal and the Wi-Fi module. Or, just keep them side-by-side, instead of in a stack.