WIN 7 failure to exit hibernation after power loss
A couple of times, power has been inadvertently shut off during hibernation of my WIN 7 64 bit computer. At the resume screen, the keyboard was not recognized and reboot was not possible.
At first, I thought that the problem was due to the unavailability of USB support but, after some head scratching and google searching, I have changed my mind and decided that I should expose my finding for other lounge members.
I had forgotten that, due to USB cable length insufficiency, I have connected my keyboard and mouse via a miniature powered hub located, invisibly, behind the computer case.
When I attached the two cables to the real USB ports on the computer case and rebooted, the keyboard and mouse were active.
I am pretty sure that the problem was caused by the lack, at boot time, of a driver for the USB hub itself rather than any real USB problem. So, if you experience this sort of difficulty, make sure that your keyboard and mouse are connected directly to the real USB ports and not to a hub.