When I move windows around on my dual monitors, Toad pops up the login window and a processing box with running seconds. Neither will go away until I restart Toad. It doesn't matter if I move a Toad window or a window from another program.
Delete the NVIDIA drivers and restart your machine. When you restart the machine it will rediscover the 2nd monitor and allowed you to reconfigure it. Once you do this the issue should be resolved.