I'm running Windows 8 trough Boot Camp on my 15" MacBook Pro Mid 2010 (Model 6,2). This has been working well for a long time. Since yesterday I'm having this issue though, that Windows boots to the welcome/login screen and when I try typing in my password nothing happens.
The cursor is in the password box but the box seems to be not working. The keyboard works otherwise (Space brings up the login box for example). I have tested this with both an external keyboard (the one I'm typing with right, now from OS X) and with the built-in keyboard on the notebook. I have tried with all peripherals disconnected leaving only the power cord plugged in; same result.
As a hint: When I go to the accessibility icon and try to load the on-screen keyboard, I get an error message "The on-screen keyboard could not be loaded", which shows only for a split-second and disappears.
I have wiped my Windows partition and installed Windows 8 from scratch, following with an upgrade to 8.1 from the store. The software I installed was fairly basic and well known: Java, VMware, Photoshop, Steam, Wuala. No fancy stuff.
I managed to boot into safe mode with networking once (it's harder than it should be) but there was the exact same problem.
This is really frustrating. I have no clue what's causing this or what I could do to fix it.
Any help is appreciated.