I've got an Apple Mouse connected via cable directly to one of my iMac's USB sockets. It seems to be disconnecting and reconnecting intermittently, with it repeatedly becoming unresponsive for short periods of time. Clicking and scrolling doesn't work. I can see the scroll bars of apps diappearing and reappearing which happens in sync with the mouse becoming unresponsive. You can simulate this by unplugging and plugging the mouse. (Many MacOS applications (Finder, Mail, activity monitor, terminal, etc) show permanent scroll bars when a mouse is present and auto-hide scroll bars when only a touch pad is used, for example. At the same time there is no issue with the keyboard it works even when the mouse doesn't. The same happens when the mouse is plugged into the keyboard's USB socket. The periods of unresponsiveness vary: it seems to be less after starting the computer and gradually becoming more frequent. Unplugging the mouse and replugging it into a different USD socket also makes a difference: most of the time the issue becomes less frequent before it happens more often (which is every few seconds). The issue arose after I updated the OS to 10.14.5 (not immediately but a few hours later on the same date), and I'm not sure whether it's connected in any way. Here is what I've tried to resolve the situation: • Use a second Administrator user • Run iMac in Safemode • Disconnect all peripherals • Disconnect from the Internet • Reset MVRAM • Reset SMC • Reapply MacOS update 10.14.5 • Use a second Apple Mouse None of the above have changed the situation. Apple Support Chat don't seem to have any further ideas. I would be grateful for any tips and help here in the forum, because at times the computer is almost unusable. Also, any ideas whether this is a software problem or a hardware problem, e.g. faulty component to do with USB? Attached are some screen shots of the USB section of the System report and from the Activity monitor (if that helps). Thank you for any answers!