iMac 2017 5k bluetooth and usb doesn't work

I have a problem with my iMac 2017 5k that happens quite often. Suddenly appears on my screen " Connection Lost Mouse " and " Connection Lost keyboard" , and at the same time every usb port on my mac stops working . i cannot plug in a mouse i can not do anything and every time i have to press the power button to shut it down and powered again . after the hard restart everything works perfectly until the next time .. ( that happens every day and sometimes 2-3 times per day )