Our laptop has been used in a docking station for months, and today I took it out to use it independently. No go. I could not log on. Do you have any idea how maddening it is when Windows keeps asking, "Did you forget your password?" when you know for certain you did not?
I tried all the obvious things—CapsLock on? NumLock on? Making sure they were both off had no effect; I still couldn't log on. I'm writing the saga so that (1) I won't forget, and (2) it might help someone else as clueless as me.
Next step: put it back in the docking station. Worked fine. (See, I told you I didn't forget the password.) Took it out again. Didn't work.
Tried the old Ctrl-Alt-Del twice to get the old-fashioned logon screen. Still didn't work, but this enabled me to type into the username blank and actually see what I was typing, instead of a bunch of asterisks. Turns out one of my password characters is a letter on the number pad part of the keyboard, and even though the light indicated that NumLock was off, the keyboard was producing numbers, not letters.
Okay, problem diagnosed. Now what? A Google search, of course. The first suggestions were to take the keyboard apart and clean it. Not only was I not up for that, but I didn't have high expectations of it working, since the key obviously toggled the indicator light on and off—just not the actual function.
The next several suggestions were to meddle with the BIOS. I don't think so!
Finally, I found one that said to hold the shift key down while pressing and releasing the NumLock key. Presto! Problem solved. I don't know what it actually did, but it worked, and for the moment that's good enough for me. I hope writing the story here eventually helps someone else.
UPDATE: Thanks to Stephan's suggestion, I now have a permanent solution rather than one that has to be renewed every time I reboot: At the user login prompt, type Shift/NumLock, then turn the machine off before doing anything else.
Back in the 70's I sometimes thought computing was half voodoo. Now it's up to 90%.