My Windows 8 computer has today started booting up (or possibly restarting) with the USB ports disabled, which means that my USB keybaord and mouse are not working, and I can't log in. I can press the power button, and the PC seems to power down (or go into sleep or hibernate - I can't tell). I can press the power button again, and it seems to power up again (or resume from sleep/hibernate). But the mouse and keyboard are dead, so I can't do anything else. I can get into BIOS by repeatedly pressing function keys during boot-up, and then the mouse power light comes on, and the keyboard works, so I know this is not a hardware problem.
What is Windows likely to have done that has disabled the USB ports? Given that I can't get into Windows, how do I correct this?
Thanks - Rowan