Goto the device mgr. and check status of USB, if any red/yellow flags, correct the problem. If none and reports back OK, then using another USB device, check the status when those are plugged-IN. If again, OK, see if returning to a "restore point" when it worked well, if that corrects the problem if recent. The last option is to de-install the Canon setup and then reboot and try an install again. Try cleaning the actual USB ports themselves, some get dirty or dingy.