Optiplex 3010 - Usb keyboard/mouse stop working

Good day.

My Dell Optiplex 3010 runs on Genuine Window 8.1 Pro with all the latest updates as well as Dell updates.

Every now and then the keyboard and mouse usb connections fail. The computer does not freeze, as when I move the usb plugs to other ports it sometimes comes back and I can carry on working.

On other occasions it has happened that all the usb ports at the rear stop working and i have to do a hard restart using the case power button.

Has someone come across this and have they found a permanent fix?