This keyboard has been working fine yesterday. Today I start the computer and it stops working somewhere during the Windows logo animation (I keep toggling the Fn key to check). It doesn't react to keys at all, but if an LED is on when it dies it stays on. The keyboard works fine in the BIOS. I don't recall changing anything in the BIOS. I didn't install any updates.
The keyboard is still recognized in Windows in the Device Manager. It's listed as "Standard PS/2 Keyboard". In the properties it claims "This device is working properly." I have tried to uninstall it there, rebooted twice, but it still doesn't work.
Edit: Tried to restart with the keyboard plugged out, then restart again plugged in. The computer is always turned off completely over night, as I turn off the switch on the multi-outlet.
I tried F8, Boot logging, and the ntbtlog.txt says
Loaded driver \SystemRoot\system32\drivers\i8042prt.sys.
I tried booting from the Windows CD, and even there the keyboard is not working.
Edit 2: Ok, now it's getting weird. I boot from some Linuxy rescue CD. It gives me a couple options, I select Boot Manager (PS/2 keyboard is working here). I select the active partition, boot from it. Guess what, the keyboard is now working in Windows. Great! I restart, booting normally. Aaaand: Not working! Boot again with the rescue disk, now it's working again. So, yeah. I'm typing this in Windows on the "broken" keyboard. Do I have to boot from this disk from now on? What is so magical about this boot sequence?
Edit 3: Maybe another clue: When I boot normally, the keyboard is working at the beginning of the boot sequence. Then all 3 LEDs light up for half a sec, then the keyboard stops working. When I boot using the rescue CD boot manager, it's the other way around: The keyboard stops working as soon as I hit enter in the boot manager and the Windows logo pops up. Then, during the Windows logo animation, the keyboard starts working again.