Hi again, thank you both for your time.

I don't see this happen at all with the keyboard. It just happens with the mouse, and it can happen at any time. I can be logged in for hours, or logged in for 30 minutes. I can either be idle, or I can be in the middle of an instance, or in a city--there doesn't seem to be anything causing it.

To Packetdancer: It's running as a window. This is the first time I've seen this occur, however, in over two years of running this game on this machine, so I don't know why it'd change now? And I've seen it occur whether or not my second monitor is on (i.e. all windows on one screen vs. some windows on a second screen). For example, it just happened tonight, and my second monitor was not on (and it has happened in the past when it was turned on). For reference, the second monitor is a tablet monitor that I use to draw.