New
#11
I'd be curious too. A lot of people who use USB keyboards and mice have this issue. I go around it by using a PS-2 Keyboard to get into windows, and then windows loads the USB drivers. It's quite possible you were able to log in and Windows automatically downloaded the drivers.
Many new systems don't have a PS-2 port, but they are included for problems just like this on most new machines, they usually have one PS-2 port that can be used for KB or Mouse in case Windows does not have a native driver on hand for the USB devices.