i have an unknown icon in my menu startup bar location. I can't remove by known methods like holding the cd key and dragging it out or right clicking on it for more detail or using the option click to get information. Also, it doesn't show up in activity monitor. I'm at a loss for next steps. the icon is simply 2 opposing arrows, one aimed at the upper left corner and one at the lower left corner. Any ideas on how to remove it?