[Blarg]

I have weird things like this go on every once in a while. I will power down my computer and it will start up again with one of the screens black or with the settings messed up(wrong resolution, the taskbar on the wrong monitor, whatever.

I have always been able to work it out by disconnecting the cables for the secondary monitor, powering down, and powering up a few times with only one monitor selected, either one of my two. It seems my system resets funny sometimes, and powering on and off with a few minutes wait between the two matters. I often find I have to unplug the computer, too, to get it really starting from fresh and not with anything saved in any kind of memory state or whatever.

Anyway, sometimes this takes 20 minutes of screwing around and it never seems to work with quite the same cable shuffling twice, but you might try just brute forcing it like that with simple on and offs and starting from one monitor. It has worked for me many times.