It has happened twice already, and both times, the computer completely froze. I could move my mouse, but no matter how many times I clicked, wherever I clicked, nothing worked. Since everything pretty much stops working, I haven't been able to right click on it and see what menu might come up or if there's any information on it. I took a screencap before I restarted. I hope someone here has seen it and knows what the hell it is. It's the arrow encased in the not-at-all-obvious red square.