With the usb problems can only suggest downloading SP2 again from here; click here hopefully the over installation will cure the usb drivers. Make sure nothing connected to any usb ports whilst installing.
The ripple effect could be graphics drivers.
Download PC Wizard, should give info about GPU and updates. click here
Download the graphics driver updates to desktop then go to control panel and uninstall original drivers. After reboot install new drivers. Will need to reboot again.
Hope that helps.